I own a couple of high point balancers as well as a Top flight. I do not own a Windsor Master Airscrew balancer.

They are only available in 5/16" & 3/8". This leads me to believe that the Master Airscrew props come with 1/4" holes. Drilling oversize off center would work but you cannot drill a 1/4" hole off center with a 1/4" bit. (When there is already a 1/4" hole there.)

APC's have a step hub in them. If the smallest step was 1/4", you could redrill it to 5/16" or 3/8".

If the small step was 5/16", then you could only balance it for 3/8" prop shaft.

One solution is to bush the 5/16" hole after your done with a piece or two of brass tubing to get it back down to 1/4". Or likewise you could rebush a 3/8" hole back down to a smaller size.

Go to Google and do a search for Windsor prop. It should be the first thing that pops up. I think the balancer is listed under assessories or tools? The arbors and the balance are priced seperately. The arbor is like 24.95 and the balancer is 14.95. It looks like the arbors would work on a High Point balancer. They might possibly work with the Top Flight if they are pointed and magnetic.

Good luck

Jim