I use a similar method and I heartily agree with the WD40. It also helps if you excite the valve (hit it briefly with 12v numerous times (be sure to keep the spark away from the carb cleaner).

The point to the movement and the WD is that you can't really spray where the accumulation is most important and after you are done the left over crankcase dung will be very sticky. The WD keeps it from sticking as it dries.

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician