I had intermitent starting problems with mine, I ended up replacing two relays and the clutch engagement switch for about $20.00 total.
The original relays were Bosch at about $15.00 a piece, I cross referenced them to Stens and got two for $12.00. Also found the Stens version of the clutch switch.
Also about two years ago I put in a starter assist kit, Hustler #107910.