O-ring??????
Never seen that but we do atleast one a month with no reverse due to the clutches wearing out or otherwise failing. Every so often one of those so packs the governor passage screen with clutch debris that the unit also won't shift.
A repair of just the reverse clutch can sometimes be had. It will cost half or more of the real job. I haven't done one in years because it is plain stupidity to enter an antique mechanical device, spend half of what its worth to accomplish a small fraction of the repairs that would done if repaired properly.
The logic says the seals throughout the device are all 17 years old, the debris has likely progressed through the filter system into the
VB screen to the governor requiring further disassembly.
There just aren't a lot of alternatives for a loss of reverse on that trans. Combine it with other symtoms and its rebuild time or replace time. The cheaper option to a quality rebuild is to spend half that amount (or maybe more) or a working 17-20 year old junk unit.
One other low probability option. The filter may be so plugged that replacement might allow driving the thing far enoughy to dump the problem on someone else.
