Have you drained the gear box oil for clues as metal in the
oil? Pulling the gear box cover will possibly show you the issue. Have you noticed any signs of metal in the past services? If it’s gears, bearings or Etc
in the box, hopefully you will easily find parts. When you find the problem, try to link the
cause. “Good Luck”!

IMHO, pull the engine, loosen bolts holding two sides of trans and drain oil, put tiller on it's side, remove one wheel, split trans and see what's going on. Make sure you have the exploded parts list for the trans before you start. If I recall correctly from other posts, often the upper portions of the trans develops rust and freezes things up, as oil doesn't get up there. Clean, lube, etc. if required. Also, you'll have to have a new gasket for reassembly I also seem to recall the OEM one is Xpensive and is essentially a piece of paper or very thin cardboard. RTV or similar was used in reassembly. Also do a search on youtube for tiller transmission repair there's various ones. I'll try to attach one.

https://www.youtube.com/watch?v=TWPvZiIWkQA

If this looks like more than you want to tackle, local small engine guy or, given the age, replace and sell the engine on CL to lessen the pain.

Good luck,

Ev

Very Good Videos, Information
and Lots Of Work. IMO some digital camera
shots would come in handy disassembling and reassembling due to the excess of
work.

My Tiller Repairs were front
tines with cast gear boxes and gear oil vs grease. Pulleys and chains were involved with some simple
tillers. Except one small Honda Tiller
the case was welded and no replacements parts offered. We ground the weld to enter the gear box and
saw the bad gear. My friend opted to buy
another new gear box as recommended.

IMO, if you had excessive
wear on pre 1990s “maintained equipment and reasonably used”, it was not just
one warned part and you had reasonable time and service from it.

Hi guys! Thanks so much for the help. So I look around at the belt. There have been issues with that since the day I got it. I opened up the gear box, and I found two gears that are torn up. I looked up the parts for it... and they are "obsolete" at the sears website.

Here are the part numbers and description according to the manual I downloaded. Any clue as to where I can find these parts affordably? The tiller model is 917-299691. Here is a picture of the two parts. Thanks everyone for your help. It has been very valuable

917 translates to Roper/Frigidaire so that's an older tiller. You might try googling AYP+ part number and it'll show who has it for sale. WARNING, a lot of small engine sites indicate they "have" a part but when you ordr and pay for, it becomes backordered as they don't have it and order it. A month or two down the road you make a fuss and they refund your money.

Good luck,

Ev