I would never, ever, ever, put a pinball machine on coin drop in a comic book shop. If I ran a comic book shop, someone put in an Avengers LE with a topper and headphone set, let me keep 100% of the coin drop, I would not want it in my store. I LOVE Pinball. But the whole business model behind a comic book store is people coming in for one thing, loitering, and buying stuff on impulse they didn’t know they wanted or just happened to be in stock. The playing board games in the store is largely feeds store business as it is usually mostly geared toward tabletop mini gaming or card games, with booster packs and new models conveniently available (for a fee) inside the store. You know what people who are playing pinball are not doing? Getting beaten by other people in board/card games where you can buy better cards (at the store) to compete/get better. The pin would take up valuable floor space, and the noise (even with headphones) could potentially annoy other customers who can easily walk into another shop to get what they need. It could also distract employees who should be organizing the dollar comics that are always out of order.
The only scenario I could see even coming close to working would be if the pinball machine were used as a way of driving the business of the Comic book shelf itself. Pinball machine is not available on coindrop, but you get a free game with every purchase, limit one per day. There is a monthly giveaway prize for the highest score and your name is in big letters (last months champ was jim-bob!), win Spiderman Compendium one signed by a 3rd rate artist for this month’s high score. This would limit customers to 1 game, might drive repeat trips to the store and your store over other stores. Finally, this would imply that people were only playing pinball AFTER making their purchases, which would mean (other than floor space) it would not be competing with the store’s business. Most rando’s playing pinball suck.
Also, on the Union thing. You work for a very small business in a position that lots of people would give fingers for. Certain positions, like working at an aquarium store (me old job), working in a comic book store, or working in a video game store have way more people wanting to work them than jobs available. I would strongly recommend against going down that path over a pinball machine.
The most common business model for pinball is people coming in to play pinball where the establishment breaks even on the game, but people buy beer/food. In around DC the only exceptions to this rule I know of are one that raises money as a charity for Special Needs kids and educates autistic kids (Spinners) and the one at Mom’s Organic Market in College Park which is the owner of the chain’s personal collection overflow and a place where he can run tournaments for fun. The only places that have pinball machines for employee use I am aware of around us are places where competition for employees is fierce, the employees all make 100k+, and it is part of a rediculous benefits package. Look how cool our office is! You should work here! Comic book shops don't generally have that problem.