I've seen just the backplate available, I don't remember where or what the part#'s were but I know I've seen just the backplate itself. I don't see why your existing roto starter wouldn't work, it would be stupid if it didn't..

Don't switch to the roto though until after it's broken in and easier to start, I've heard of people overheating the roto start motor and it burning up because it's such a tight motor. I just use gloves, even on break in I don't have a single blister and my hands aren't messed up at all.

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