Hi Mike
There must be some reason that some people are having to buy and run a pump to have a good running engine and others don't.
If I must, I will. (BUT I WON'T LIKE IT)
The picture is the backplate of my OS 1.60. The bottom of the casing has a build up that looks like this is the place to drill.
IS THIS THE PLACE?
Great to hear you've got the CG at a comfortable location
Sucks to hear about the engine problems
Best Regards
Jim