(ET) Tiller questions: Chain and belt tension

[Chris Zach <cz alembic crystel com>]

So this afternoon I had to plant a pair of chestnut trees. Plan was to 
use the tiller to dig up the ground in a 3 foot square, then plant the tree.

Tree 1 went in without much trouble in the back; soil had been watered 
in past day or two. Tiller worked hard.

Went to the front, and tried to till. Blades jammed, and the belt was 
slipping. Shut it down and pulled the cover.

Turns out the chain had jumped up on the gear. There is a *lot* of slack 
in the chain, and the belt is not too snug either. Still, I prefer 
burning the belt to damaging the gears or something.

So:

1) What is the chain tension supposed to be? Is there a way to adjust 
the chain tension without removing links? That's a thick chain; I find 
it very hard to believe it just stretched.

2) What is the belt tension supposed to be?

The tiller had the usual bent back bolt, I'm trying to straighten it out 
a bit. Should I use heat on it to bend it back to straight?

Thanks!
Chris