Snowblower Craftsman 536.881800 Briggs & Stratton 8 HP

When shift control is moved forward to power shift position and traction lever is engaged, only the latch mechanism releases. The wheels don't go in reverse. Reverse works fine when selected via the shift control. According to the service manual, "When the shift lever is pushed into the Power Shift slot, a tab on the index wheel contacts a tab on the reverse bellcrank every other time the Power Shift is cycled." With the control box attached to the machine I can observe this area. I see the index wheel turn but the tabs do not contact the reverse bellcrank tab, so no reverse. It's difficult to figure out which surface of these index wheel tabs is supposed to contact the reverse bellcrank tab. Is there a common part that fails in this area? The indexing mechanism seems to be intact, just not aligning with the reverse bellcrank tab. Bought new in 1997. Mike

Snow blower will start on the first pull and run for a minute or two and then shut off. It then has to sit for another few minutes before it will start again. I've played around with the choke and it has new gas. Is it getting flooded, and how would I fix that? Thanks for your thoughts.