What oil goes in the gearbox behind the motor , I have a junior

Randy, The gear in the gear box may have sheared a key, or damaged gear. Check the attached links,instruction and guides, Good luck
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Tiller Gearbox Trouble
Murray Ultra Tiller Tines Won Keep Spinning
Update Craftsman rear tine tiller repair stuck gears

I had the same problem, the engine ran but the tines would barely move on my Ryobi tiller. There were 2 plugs on the gear box. I removed them with an Allen wrench and added oil until it leaked out, replaced the plugs, waited awhile and started it.That fixed the problem, it worked fine.

Make sure lever is moving shaft that goes into the gearbox, if so you probably have internal problems with gearbox.

30 weigh oiltdetergent (if available,if not regular 30 weight oil will perform also), as for the gearbox.transaxle for the tines use 80-90 weight gear lube

MAKE TWO PASSES SET THE DEPTH GUIDE SO IT JUST BREAKS THE GROUND, DON'T TRY TO DO IT ALL AT ONCE. SOON AS THE GROUND IS LOOSE IT WILL DIG MUCH BETTER.. IT SHOULD HAVE A FORWARD AND REVERSE FOR THE TINES, GEARS FOR FORWARD REVERSE DRIVE

You will have to get into the gearbox. It isn't too hard but is time consuming. Sounds like the drive for the tiller has broken. Could just be the chain in the gearbox for the tiller drive.

its possibly the gears inside the box they are spider gears & wearout on those they are great machines but the gear drives are weak most of the time or the belt could be slipping

on my pony the disc came off when i removed all of my tine shafts. then i pulled the old seals out an drove the new ones in

I have a pajero junior 1997 4A31, I am having problems, with my gear, when take off in D the car is slow, and up hill no power in 2nd & D, in Load ok. Plse advise. Thank you.

The tines sometimes get frozen to the shaft. You might try penatrating oil and use a heat gun or hair dryer to heat to loosen.
Also tap wiht a hammer around shaft.