My son has an older Bolens riding lawn mower. While it shifts and operates in reverse OK, it does not do so in forward. You have to jiggle the lever to get it to engage, and continue to do so to keep it running forward. What can we do to correct the problem?
It sounds like it could be something binding up in the linkage, or something that is loose.
I would take a look at the parts that move when you push the lever and see if you can find anything that is binding up or is simply loose. It may be something as simple as a loose nut or bolt that is causing it to not grab somewhere like it should.
Guys, I solved the problem today. It turns out the the shift handle to the left of the drivers seat engages a horizontal rod that goes into the transmission. (Reverse is rod-out; forward is rod-in.) The connection of the shift rod to the transmission rod is via a bolt and nut thru a slotted hole. It turns out that the slot was not long enough to allow the transmission rod to enter fully. The solution was to lengthen the slot, using a combination of file and reamer.