How to fix a John Deere Snowblower?

I’ve got an old walk-behind John Deere Model 526 snow-blower that’s gradually lost more and more ability to throw snow well. Originally I thought this was due to a combination of several things (i.e. an old engine and/or unusually wet snow that stuck easily in the snow exhaust chute).

This winter, however, I noticed by accident that when I applied forward pressure to the Engage/Dis-Engage Lever (after it was placed in the Engage Position), the more pressure I applied, the further the snow was blown. A parts diagram of the snow-blower shows a part called a drive disk that could be something like a clutch in the units snow blower section. Would replacing this drive disk be much of a job and would I need any special tools or adjustment procedures to re-attach any disconnected mechanical linkages?