Ouch, have 94 1.8 Eunos, cars a piece of cake to work on. Cam belt and water pump a lazy days work on the drive. Very little to go wrong, rust seems to be the number one killer
Yep tin worm is a huge problem with the MX5 the earlier ones were much better but the later ones were made to the American market specifications, crumple zones up front, Mazda made the chassis out of much thinner steel but made it a double skinned chassis, the trouble is water gets in between the skins into the cavity between them and then rust from the inside out, you cant see the problem developing until its too late.
I bought an 2004 three years ago and keep it for 24 hours returning it to the garage for a full refund. I had an engineer look over the car and he said it was not fit for purpose and not of merchantable quality he said take it back and ask for you money back and if they are not helpful tell them that you are going to take it to an MOT station and have it Officially MOT'ed and when it fails which it most certainly would because you could push your fingers through the chassis and through the floor pan close to the rear suspension,. They would then have to give me my money back as it was an MOT failure and should not even be on the road, Plus the car they took back would not have an MOT on it as the most recent MOT to be done is the one that stands with the authorities.
I then searched for a nice MR2 Roadster found one and purchased it, no rust anywhere on the car body or chassis, Mid Engined 1800 vvti lump, rear wheel drive, Limited Slip Diff (Great for Donuts).
I fitted a Stainless Steel Manifold doing away with the two Precats that are located in the manifold, this removes the issue with the MR2 engines when the precats start to break up.
Great little car quick, revvey engine that wants to please and in my opinion looks much better than the MX5