Charlie,
Speaking of a weak reverse, the 129 has almost no reverse.
I have tried adjusting the linkage and even went as far as loosing up the linkage plate and adjusting it as per the manual to find nutral, and still have very little reverse.
Now I have notice that the PO might have used the wrong type of hydraulic oil in the trany, it is a butterscotch color, not red like Hy-Tran.
I have gotten a new filter and 2 gallons of Hy-Tran to change out the oil, even picked up a new rear cover gasket so I can clean out the bottom of the tranny.
My hopes is that after I change out the oil and filter with new it will pick up on the reverse. If not, how much of a job is it to change/ repair the reverse valve? or is it even possable to do so?