Any chance you could post a picture of the part in question?
 

The 400 was the begining of the fazers and was built for the Japanese home market in 1997 and 1998. The model code was 4yr and many of the 600 parts begin with 4yr. It put out 53hp at the crank
The 600 was derived from it and was in production from 1998 to 2003 with an update in 2000 and a further update in 2002. It has 95hp at the crank.
The 1000 was an addition to the theme and was in production from 2001 to 2005 with the detuned R1 engine with 143hp at the crank
I happen to have one of each in my garage. The big difference in looks with the 400 is that it has Brembo front brakes, a seat strap, no grab rail and no centre stand.
The 400 is a lovely little bike to drive with a power band at 9000 revs compared to the 600 at 7000rpm, never noticed one on the 1000 it just pulls like a train. Oddly enough even though the 400 looks identical to the eary 600 it feels much lighter.

Finally recieved a reply from Danfay, they have offered to give all the parts I require to replace the shaft at half price.
 

Frgot to add in the previous post that he put a rubber washer between the sprocket and the tabwasher

See post on Front sprocket issues again

Fazerrider,
Have to agree with you on the diagram issue. I to have spent years reading electrical diagrams in the telecommunications and IT industry and have to reset my brain when reading motorcycle wiring diagrams.
One of the best places to start is disconnect all the connectors in the box under the tank spray them with WD40 and reconnect them. This is the first thing I do when I get a fazer with electricl issues, it has solved 7 out of 10 of the problems .I have seen cases of broken earths causing strange problems and it is a likely case.
Since you are familiar with electrics remove the Orange and Grey wires from the coils and with the iginition on (and kill switch on) and spark plug earthed against the engine tap the wires off an earth and the plug/plugs should spark. Thay rules out the coils. The only thing common after that is the CDI.
It may be a CDI issues as His Dudeness suggested as it is common to all, but why a bump should cause it is strange as it is mounted on plastic and rubber. I have never heard of one fail, but there is always a first time.
As far as I remember the 02-03 one is a different part number to the 98-99 one, but there are available on ebay.
 

Not necessarily as some of the cutouts have bypasses. eg neutral switch  bypasses the side stand switch, and clutch switch bypasses neutral switch. etc.
Forgot to mention the Cam cover is insulated from the engine with rupper gasket and rubber seals on the cam cover bolts so there would be no spark there.
The fact is stopped dead is definitely electrical. It could even be a dogy ignition switch as it has 8 connectors within and at 146k it would be well worn. One contact of the ignition switch powers the speedo via the backup fuse which in turn connects to the speed sensor which has a connection to the pick up coil and TPS

 If you can do the basic servicing yourself then what you have mentioned is not beyond your ability.
 It can be a good idea to take a few pictures before you start to ensure all goes back together the same way. J.
 I take it you have a Haynes Manual and downloaded the Yamaha service manual from the downloads section.
 I would recommend you buy a good quality torque wrench, as the biggest issue I have come across over the years is home and shop mechanics over tightening and stripping nuts and bolts. I own 3 torque wrenches.
 They are: a 3/8 inch drive 2 to 20 NM, a 3/8 inch drive 10 to 50NM and a 1/2 inch drive 20 to 150NM. The third one covers most bolts and nuts on my car and a few on the bike. There are a lot of bolts that require between 5 and 50NM torque on a motorcycle and at least you will know they have been tightened properly. You would by the two 3/8 drive wrenches for what the dealer would cost. They will be your best investment in the tool box but always wind them back to zero when finished using them.
 Wheel bearings: Remove the callipers or push back the pads and check for movement by holding the wheel top and bottom and push pull in line with the axel, should not be any movement, Take wheels off and check for roughness in the bearing. Both checks are simple when changing tyres since you will have the wheels off.
 Steering head bearing: any clunks or clicks when breaking and is there any roughness, notching or tightness with front wheel off the ground turning the steering side to side. No, leave them alone. Yes dismantle and change them. Not inclined to give trouble unless you wheelie a lot.
 Are for fork seals, leaking: Yes change them, No, leave them alone.
 Since you have a centre stand it makes checking/greasing the swinging arm an easy but time consuming task. Remove rear wheel. Remove bottom bolt on shock. Remove caps covering swinging arm pivot bolt, undo pivot nut and pull out the bolt. Remove swinging arm. Don't lose the thrust covers at either end of the swinging arm and with swinging arm off remove the suspension arm/dog bones bolts.
 The most difficult time consuming job at the 24000 mile service is checking the valve clearance and since that is mostly a dismantling/reassembling job you should be capable of it.
If you are happy with the above then I could post method of checking the valve clearances and changing the coolant. Changing the coolant is nearly as easy as changing the oil.
 
 

Short answer NO
Just keep up the regular maintenance and it should be fine. Obviously the maintenance intervals will come around more often and don't skimp on the maintenance  as it is false economy. Mine has 72000 miles on it and still going well

In my experience 10mm is to much. 5mm is probably the best compromise. It does sharpen the steering even though it is very good as standard. If you have the preload adjusters set the stattic sag to 23mm and work from there
 

The disks on the later Gen 1 have a different centre carrier which would make them slightly lighter, but they are interchangeable with the earlier models. According to Yamaha the later model disk superceded the earlier model disk

Absolutely no reply from Danfays to my email, will email again. There spares section might be good but their service and sales are crap
Fix still holding after 1300 miles

Short answer, yes
Same pads, same calipers.