Get your local association involved. We had to do that in one of our leagues when the Spectre was banned because we had a guy that kept trying to use it in league. He showed up the first night after the ban with it, and I told him I couldn't allow him to use it without protesting, because I had just lost mine to the rule change, too. He had other equipment with him; his position was "I paid too much money for it to just let it sit." We had to raise a fairly big stink with his team captain, and then go get the owner of the pro shop to explain the situation and make him keep it out.
Unbelievably, about 2-3 weeks later, I look on the lanes adjacent to me, and there's the same guy with the same Spectre. The opposing team captain knew about the ban and here we all went again. He didn't use it.
I figured that was the end of it, but his team ended up qualifying for the Final Four round of our league playoffs. He inexplicably shows up with the ball. This time the team he's bowling doesn't know about it. Me and the team captain from the team we were bowling on the adjacent pair skipped all the pleasantries and went down to the association secretary, who happened to be in the building. He comes down to talk to the guy, and the guy's not hearing it. He keeps saying the team they're bowling that night doesn't care, so why should everyone else (answer: it's a Final Four playoff, meaning they're technically bowling three other teams, not just one -- I don't think he understood the format). Our association secretary more or less told him that if he started the game with the ball he was going to order the scores vacated. It got testy for a few minutes but the guy eventually relented. He bowled like crap with an older ball and I haven't seen him since.
The rule that really has caused an issue is plugging the thumbhole for no-thumb two-handers. That one has nearly started a couple of fights but so far no one has done anything more than just vent a little before taking the ball out of play.
The key here is you have to have good league/association officers. If you don't, some people are going to bully their way through the process. Rules either matter or they don't. I ended up plugging 30+ balls during the time I switched temporarily to no-thumb, at a not-insignificant expense. It's kind of what you have to do.
