Driving today suddenly I had almost no clutch, biting very very low, A wearing clutch would, I assume gradually get worse, whadyareckon, and how do-able is the job, my bro is a mechy and has done a few clutches, but he mentioned something about an alignement tool, is there a known army dodge on the forum.
The alignment tool is only there to make sure the splined hole that the gearbox input shaft slots into in the clutch plate lines up, so when you offer the gearbox up to the engine it all slots together ok. Remember when you do this that the clutch will be engaged so the plate will be clamped down by some pretty hefty springs, making jiggling it about pretty difficult.
Clutch alignment tools are cheap as you like, but if you really get stuck, get yourslf a piece or dowling almost big enough, then wrap the end with pvc tape to bring it up to the correct diameter. Bobs your uncle, DIY alignment tool. Not pretty but it will do at a push.
Is the 155 clutch hydraulic? I never noticed the extra gubbins.
Anyway... missus had the same problem with her brakes not long ago. The O-Ring seals in the Master Cylnder had croaked. If there's a hydraulic clutch it will have the same set-up. You should be able to get a repair kit (new O-rings) unless the internal cylinder bore itself is scored, in which case it'll be a new M/C.
On my 164, the clutch pedal got stuck to the floor. I could release it with my toes and it was OK for a while. The cylinder made a lot of squeaking noise. Replaced it, problem solved . In a 164 replacing the cylinder is a hell of a job, due to impossible place. Though it was done in an hour.