Small Engines (Lawn Mowers, etc.): Peerless Tecumseh MST 205-547 Transmission, belt tension, tractor mower

Question
My Hayter 13/30 Tractor mower will not move forwards or backwards. As the belts have been on around 6years I assumed that worn(stetched belts) were the problem. After replacing both Mower Deck drive belt and Motion drive belt I am still left with the same problem...Will not move. I have checked the motion drive belt tension which is good when clutch released. I read on numerous blogs people having the same problem which in 99% of the cases came down to the transmission. I have dropped the transmission and opened it up and everything looks very good, no obvious signs of wear so I have come to the conclusion that it could well be the shift keys, so I have just ordered a replacement pair. Can you tell me what to look for and tests to carry out to check the gearing function whilst the transmission is open as I have n't got the faintest idea what to look for?

Many Thanks
Keith

Answer
I really hope you have a transmission problem and not something simpler. It sounds like you may have had a key missing from one of the wheels. It only takes one key to be missing for this to happen, so if this is the case, that could have been the problem. The only way I know of to check the transmission is to assemble it with just a few of the screws and then put the pulley on and rotate it by hand and watch the axles turn. If they both turn, hold one and watch the other turn as the other is held still, this will verify the differential is working correctly.