Volvo 2030/MS2L gearbox problem

[andf]

My shaft drive VP 2030 with a MS2L gearbox has started jamming in reverse (whilst under power) causing several recent 'brown trouser moments' in tight spaces.

I've eliminated external controls so the problem is internal to the box. Ring any bells with anybody? Any ideas what the problem is likely to be?

Courier

 

[Heckler]

They are a v simple box, two cone clutches and gears, in effect you shove a cone into contact with a mating face. so the only thing that should hold it in place is the linkage in the box. However I suppose if the cone gets really worn it could go too deep into its mate and bind. Disconnect the linkage and shove in to gear by hand on the side of the box, see how far the lever travels when you select revers and also the same for forward. if they are significantly different then maybe the cone is worn. The boxes are easy enough to strip but the bits are expensive.
Stu