Leaks oil around the tines.

without a proper model number it is guess work, but either the drive belt has snapped, or if the right wheel drive the left wheel, there may be a half moon key way or a shear pin. General help here, followed by parts suppliers

https://www.google.com/search?q=Troy+bilt+horse+tiller+right+wheel+turns%252C+but+left+wheel+doesn't+turn

Garden Tiller Parts - Troy-Bilt

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Find the tiller parts, including blades, belts, tines, seals and replacement part kits, that fit your Troy-Bilt outdoor power equipment. When you need garden ...

Troy Bilt Horse Parts Lookup by Model - Jacks Small Engines

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Troy Bilt Horse Exploded View parts lookup by model. Complete exploded views of all the major manufacturers. It is EASY and FREE.
‎Horse i 7hp roto tiller (s/n 1001... · ‎8HP Electric PTO Horse Tiller · ‎2308 Horse III

Garden Tiller and Cultivator Parts ' Troy-Bilt US

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Find the tiller parts, including blades, belts, tines, seals and replacement part kits, that fit your Troy-Bilt outdoor power equipment.
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Troy Bilt Horse Tiller Parts

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Troy-Bilt Horse Tiller Part Search. Search the part you're looking for by part number or model below. Troy-Bilt Part Number:.

http://www.hammerwall.com/Manuals/Troy-Bilt/Description/21A682J766/Troy-Bilt%208%20HP%20Rear%20Tine%20Tiller%208%20HP%20680%20Series%20Briggs%20and%20Stratton%20Engine%20Manual/275092/

sounds like you are trying to till too deep raise tines up a little with the depth gauge then till the same spot again and see if that helps

The wheel shaft on a Horse tiller is one piece so if the shaft turns on one side it will turn on the other. make sure the pin that holds the wheel on is not missing that would let it spin on the shaft.
That's the only thing I can think of that would cause that problem. Hope that helps.

Frank

If you email me at [email protected] I have a couple of Econo-Horse manuals that I downloaded that I can email to you. They don't really have a clutch just belts and pulleys so its probably just needing a new belt or a belt tension adjustment. I have a Econo-Horse tiller and it is a nice machine I think mine is about the same age as yours.

Good Luck,

Frank

Hole in the top side casting ... remove the plug. 90 or 110 weight gear oil available at yor auto parts store or other fine retailer who sells lubricants.

OReily Auto parts stores carry GL-4 straight 140W gear oil that will work for the old Troy Bilt tillers. Its around $12.00 a gallon.

You likely have a clutch problem, never saw one that a simple adjustment would fix. I'd take off the tiller (there are two bolts that hold the tiller portion to the transmission, and check to make sure the clutch is sliding in and out. My hunch is either the lever is loose on the shaft or the allen-head little bolt that they use to shift the clutch has come out. Be sure to grease the clutch while you're in there.

This should be covered in your owners manual. Shame on them if they didn't mention this.

The tines are very close to the housing and sometimes you do get rocks hitting,as for the dirt it should have side panels to keep the dirt in place.

The problem is lack of lubrication in the pto coupling. Losen the two swing bolts carefuly,block the front under the motor. Separate the tine transmision from the housing and grease both sides with as much grease as you can work in. Work the lever as you do this. Should fix the problem.