Basil:

Not terribly accurate, but better than nothing is to look through the hole in the prop hub to center it on the shaft of your srewdriver. You can get a rough balance check that way.

Great Planes has what they call the "Fingertip" prop balancer, costs a little over $4, and works well.

For reasons of appearance as well as noise, my prop of choice is the Master Airscrew three blade series. I've not had spinner fitting problems with them. Perhaps your engines just don't have long enough threads on their cranks.

Again, because they're noisy, I use the APC props only where I need their high efficiency, ie on "3D" [lanes.

Good Morning.

Bill.