model 10304 self propel problem

I got a free lawn boy 10304 silver series. It was leaking gas and I got that fixed. I sharpened the blade and took the muffler off to check the exhaust ports.
They were clean but i couldn't get the tapered blade plate off. I used a lot used PB blaster and a hammer and a puller but it just bent the blade plate. So I straightened it back and just put the blade back on. Also I greased the fittings at the drive wheels. When I started the mower up it tried to creep forward
even with the handle disengaged and it won't back up. The drive wheels are locked upand won't go in reverse. The belt seems like it has shrunk. I took the belt cover off and everything looks OK there. I have a model 10302 that is a twin to this mower and it looks the same but the belt on it is a lot looser. The previous owner said
he never had any trouble with the drive part. My question is would putting too much grease in the fittings cause it to mess up or BB Blaster shrink the belt?
On a parts website I found two part no.s for belts for the same mower. 93-7381 and 92-1043, Does anyone know which would be the right belt?
Thanks for any help.

Which belt to use will depend on your serial number. If your serial number starts with 69 use part number
92-1043. If your serial number starts with 79 us part number 93-7381. Belts don't shrink, but some liquids will breakdown the belt material, causing problems.

Take the rear wheels off and clean everything up do one side at a time if your not familiar with the drive system lightly grease and reassemble. That should help the the pulling backwards issue as far as the belt being to tight I'm not sure if it's on the two pulleys correctly it should be ok if it's the correct belt, just make sure it's not full of grass clippings or mud. I would also remove the cover from the transmission and clean and re-grease it's probably original. Good luck

What crnbinder said.... I did mine and was sastisfied, then I washed the mower one day and when I went back a week later, similar. Think i was too agressive and the ring pinion transmission was seized up from rusting. I free up and it has been OK.. Also if belt is adjusted too tight with handle control cable, it may not allow slip past belt when pull handle back.

You probably can not pull mower backwards whether running or not.