I had a similar Maillard freewheel incident. I don't have the oversized spline tool. Not much old school shops around me, so I try the neighborhood shop, a BMX and road bike specialty shop. I inform the first mechanic (young 20 something) what I needed. He looks at the 1981 wheel wide-eyed, then proceeds to try to fit a BB cup remover on my freewheel.
I said, "That's not going to work!"
Finally the head mechanic, my age comes over and knew they couldn't do it and told the other guy to halt what he's doing. He at least recognized the vintage SR hub and Ukai rim. He was honest about not equipped to work on such older equipment. Advise me to try several shops he knew of.
Wrecked Maillard freewheel and hub averted!
These days, there is a underlying sickness of apathy used to compensate ignorance in the workplace. Not only mechanics. A lot don't care because they get paid either way.
I would pull aside the owner, speak to him about how you feel and conflicted about what took place. You are now lessened a pristine freewheel for its intended display. Voice your concern about his hired hand, and how what transpired may question your trust in his shop. If he cares about his business and his valued customers, he'll do right by you.
If you walk away disappointed and irritated and unsatisfied, you know you're never stepping into that shop again.
[hellaflush]
Man, I had to look that term up! Damn I must be getting old. And yes Gene, that is the stupidest car mod I've ever seen.
