Hi Baz.
My Comp adjusters were seized too.
Put a piece of clear PVC pipe over alloy section, couple of tie wraps on tight & flooded em with decent penetrating oil, left it for wks & it did feck all, yrs of hardened crap stop any oil getting in.
Decided to do a full K-tech refurb, so dropped forks, stripped em & removed the complete Comp adjusters.
My experience is you need to get the lower leg quite hot with a hot air gun, don't heat the actual Comp adjuster itself, it's a sealed unit & has O-rings inside that may melt,.
Comp adjuster alloy housing is thread locked into fork leg, heat will crack the thread lock if u get it hot & penetrating oil down the threads & rock adjuster back n forth with a good fitting spanner, there's a special socket for the job, but it aint cheap so it was a no brainer spanner option for me.
Don't go at it too hard with a spanner, heat & lube & it'll come free, it's not that tight, unless it winds out nice & easy, work it out as if you were tap threading a hole.
Once it's cracked loose, use plenty of lube or it'll gawl the threads up, I had one that was a right mare to get out & had to be re-threaded.
Heat gun process actually helped free off the brass adjuster a bit too, but mine were coming out anyway as forks were being stripped & painted.
A few sessions in ultrasonic bath & brass adjuster screw came free & clicks as it should after a good dousing in ACF50 & several full winds in & out, they now function like new.
If considering a dremel to re-cut the brass screw slot, be super careful, there's an alloy ring around brass adjuster screw, it looks like this holds the whole centre section in place as it appears to be peened over around the screw, muller this ring & the whole unit may be leak oil/fall apart & generally be scrap?
I wouldn't recommend ever using a blow torch either, you'll very likely destroy the Comp adjuster, as it's sealed & has O-rings inside, it surprised me how much crap came out of em in my Sonic bath.
Spent ages tidying up the brass adjuster screw with rifling needle files, I made an alloy driver out of some scrap stuff, it's now my dedicated suspension screw twiddler & it won't muller the brass screw like a steel driver will.
If you go down this route & remove the Comp adjusters, there's a thin steel washer under its base, don't loose it or you're knackered.
Hope my many hrs spent in finding the above out helps others planning on attempting removing the wonderfully engineered Comp adjusters.
Cheers Yamaha "NOT".
If you destroy em, it's eBay for some more forks, Comp adjusters aren't available from Yamaha & I can't find anyone that make any that'll fit these fork legs, hence can't be bought for love nor money.
Bin the 190 & fit a correct 180 or you'll end up in the weeds.
Rgds
Gaz