Snow Equipment Owning/Operating Jacobsen imperial 30

[sailer]

I'm looking for a manual for this 1980's Snowblower. I've also come up short trying to figure out how to disengage one of the drive wheels. It appears to have two parts that have cross hatch that either turns or twists to disengage the wheel. I've been told that Homelite were made by Jacobsen, but not sure.
Marty