the pressure plate on the B clutch assembly if broken will cause no reverse as i said above..
I have a feeling the HP22 i pulled, was broken beacuse the owner tended to drop it into reverse at over 10mph
Luckily a fresh box and a lecture on how not to drive an Auto seems to have elightened him..
Hopefully i don't have to do it again in te future..
The Oil was also Black as night..
If you have sludge and crap in your sump, it's almost certainly fooked, to put it lightly
Tranny fluid should be changed regularly.
Began round two today.....
Added bottle of Liquid Moly, and ran for 10mins, cycling through gears as stated. Dropped oil. Removed sump. Oil still really brown, but not quite as bad. Sump remarkably clean, not sludge and hardly anything at all on magnet. Cleaned, new seal, new filter, and refilled including a bottle of Lucas......
Went round block.........and........... bloody awful, haha. Still no reverse and almost nothing in drive. very close call trying to enter a roundabout when it was litterally doing about 2mph for a good 50 yards, haha.
Came back, dropped oil again, still brown but definately lighter, so working through all old stuff gradually. Refilled again with another bottle of Lucas...
Dark by then, but still didnt seem any better on drive way, so guess time to give up and start looking for another box....
Strange thing is (and i get what Henry_b says about old oil providing friction etc) but although there is no or very little forward drive, it's not slipping as revs dont rise rapidly or at all sometimes, just sits there going no where... so guessing its well and truly knackered.