350 utility TA

1. TA lever forward both clutches engaged tractor moves on level ground and grades.

2. TA lever pulled to rear tractor tries to move on level ground, can hear what seems like the TA unit spinning or the TA clutch spinning.

Any troubleshooting help would be appreciated

The Ta has a defective (worn out) one way clutch. This device looks like a roller bearing with ramps for the rollers to wedge into. These ramps allow rotating motion in the direction the engine turns, but prevent turning in the opposite direction. The TA gears are inside a housing controlled by this clutch, and a second regular clutch (though smaller than the engine clutch)
When in direct drive TA forward, the gears and housing turn with the engine (the small clutch locks the main clutch shaft to the TA case making it turn 1:1 with the engine.
When the TA lever is pulled back, The little clutch is released. This allows the TA gears (planetary gears like in a auto trans) to operate. this makes the TA gear case try to turn backwards. The one way clutch prevents this from happening and reduction happens. Unless!!! that one way clutch fails. Then the TA case rotates backwards and the tractor doesn't pull, either at all, or only weekly. So the repair requires the splitting of the tractor at the TA housing to Transmission, and at the bell housing. Not a terrible task with good blocking, and a cherry picker. The support of the engine and front end is important.
TAs are better than sliced bread. The tractor is workable as is, but deserves a TA. (I own a 350U and it has the original TA and was used hard.
Moving the stick like it was a toggle switch, snapping rapidly in either direction is the key to long life. slow lever movement slips the ta clutch. Do not let TA adversaries give you the wrong impression.
The repair will cost modestly if only the one way clutch is replaced. If both clutches are replaced, 2 to 300 is probable, if a rebuilt TA is put in they are in the 550 to 650 category. Jim

Mr.Janicholson, Thanks for the great explanation it was greatly appreciated.