If your stop solenoid on dv20/24 malfunctions don't jump to the immediate conclusion its burnt out, Mine initially would not stop the engine and then would not let it start
a couple of light taps with a hammer indicated all might not be lost. firstly check for continuity through solenoid, if you have continuity it might just be stuck The cure, Slacken large lock nut, just crack it note distance from solenoid flange. Unscrew complete unit from engine,
separate solenoid from stop plunger (note screws are threaded as well as having nuts). check movement of stop plunger against spring if stiff or sticky dismantle and clean brake cleaner does a good job
check small o ring is OK. With solenoid detached shake it should rattle, test by connecting to 12v battery +to terminal body to - solenoid should activate. if not check to see if central rod is stuck in if so gently pull it out and clean and lube,
brake cleaner and wd 40. Re check solenoid if all ok re-assemble, replace unit to original location. Finally if all OK check idle speed, if different from before you have probably not repositioned the solenoid exactly. Incidentally have starter sw and 2 keys surplus if anyone is interested
Tips like this are so useful for anyone half competent to wield a spanner. They are particularly valuable for anyone like me whose faith in marine engineers is not unreserved and whose pockets are not bottomless. Great. Thanks jeffstrud Tony