So you have a 1250 with a manual peerless 832 manual transmission .
After downloading the IPL for you transmission, raise both wheels and see if they move in the same direction and that the speed changes as you change gears .
Starting with the easy bits first, while it is still in the air remove both wheels & check that the keys are intact.
IF your model has the ends of the drive shaft & layshaft visible they both should be turning when the mower is in gear & clutch is out
By far the most common problem is the shift key breaking
When it has broken, the drive shaft turns but the layshaft does not .
The layshaft has the brake on it and the drive shaft does not
Next simple check is the input shaft is spinning as it has a key that can also fracture
From memory I had to put a white dot on the top of the shaft and watch it with a mirror & strong torch ( not easy )
on some you can see the shaft under the pulley while on others the pulley comes down & covers the shaft
However by far the most common problem is the shift key breaking and that is usually because the owners was lazy and not coming to a stop before changing gears or the clutch bake pedal got out of adjustment so it was driving & braking at the same time .
Calling them "gears" is not quite correct as you really should not be changing them while the mower is moving they are really a "range", pick the one that suits what you are doing .
Key replacement is dead easy and as that is a fairly old machine, some fresh lubricant is probably on the cards .
Check all of the gears for cracking around the corners of the key slot
If cracked them replace them
Also be careful because all the edges are VERY SHARP you have been warned .
The service manual is all over the web as a free download "Tecumseh Technicians Handbook" covers most trannies including the 800 series .
