For what it's worth I've heard two theories on the masking tape. One, from someone else, the bumper was considered replaceable, and the tape would make it easier to do so. Two, my theory, was that tape around the bumper would seal the bumper against the buttplate, and dampen the sound of the cue hit, less of a void. Other theories welcome.
I have thought it was a possible safeguard for the butt cap. We know if you drop the cue on the bumper, sometimes the momentary expansion of the bumper can split the butt cap. But I never felt strongly about that idea.
He could have used it for temporary fitting, to hold the bumper in with friction, then just never bothered to remove it when he ran the screw in to retain it.
And finally, he could have known we would be talking about it after he was gone, and put it there with no particular purpose except to mess with us.
I like the last one. I just feel like it would be cool of old GB was laughing at us for all the fuss over such things.
I think I even saw once a person making some kind of conversation about exactly what brand of tape he used, that he got it at the same hardware store where he got his A joint screws.
I want to picture him in the great cue shop on the sky yelling down at us "it's f'ing tape!" and "it's a f'ing screw!" "I didn't make that part! Look at what I made!" LOL!
I like to think if GB were a machinist and had a metal lathe, he would have made his own f'ing screw.
But he wasn't. And he didn't. So he used what was available.
I told a guy in a pool hall "that's a Balabushka bumper on my Joss". He was fascinated.