(ET) Snowthrower chain alignment

[Larry Chace <RLC1 etnainstruments com>]

The chain drive sproket on my 42" snowthrower wants to migrate away 
from the motor until it contacts the side of the housing where the 2" 
diameter inspection hole is located.  I loosened both setscrews (at 
the key and 90 degrees away from the key), moved the sprocket back to 
where its hub was in line with the end of the motor shaft, and then 
re-tightened the setscrews.  After running for about 5 seconds, the 
sproket moved away from the motor once again.  I put as much force 
into the Allen wrenches as I could (I think!).

Looking down the chain from the auger end, it appears to run at an 
angle, with the drive sprocket "out" too far.  That is to say, the 
two sprockets (motor and auger) are not lined up with each other.

The drive sproket was new a couple of years ago, purchased from 
either Jim or Harold, along with a nice new chain.  It is possible 
that it has been rubbing against the housing for some time -- the 
unit makes quite a racket when running.

That raises a few questions:

1. Which way should the drive sprocket be installed on the motor 
shaft, with the hub towards the motor or away from the motor?  (Mine 
is "away".)

2. Is it possible that the motor shaft is at slight angle, not 
perfectly parallel to the rotational axis of the auger?  If so, how 
do you get the motor aligned correctly?

This is likely to be cold, dirty, oily, heavy work -- not fun at all!  ;-)

Many thanks in advance for any advice!

Larry Chace, Ithaca, NY  I-5 and E15