hi, I am also stripping a lister lh150 gearbox. It hadn't been run for years and had sat on shore. when I got it, it ran great. after a few hours driving I was really struggling to find reverse at all, so I checked my oil levels and realised I had lost a significant amount of oil, it appeared to be seeping out of the back plate of the forward piston, so I drained the remaining oil from the box and refilled it with SAE 80 - 90, (was mid journey home of my first narrow boat drive and I just wanted to get back so decided to continue on, regularly checking my oil) it ran okay for a number of hours (and got me home) but seemed that anything over 1/3 throttle appeared to slip instead of putting any drive through. this slowly got worse and worse and now will hardly spin the prop at all.
After reading a lot of yours and others posts, I decided that it must be clutch plates. but now I have it apart they don't appear to be particularly bad(not like the ones you have posted photos of) but they where covered in oil that appeared very thick and dirty, and the grooves in the metal plates where densely clogged. Im not sure if this clutch is meant to be covered in oil or not..?!
the reverse band has around 1.5mm of pad on which is grooved a little, the forward cone has around 2mm which appears in good condition.
any advise at all would be great!
thanks in advance
Anthony