Just an update, I picked the tug up from the shop, declared fixed. They did a bunch of carb, fuel, primer, & other work, even including a new boot & wire to plug.
I started it twice, let it run some. I'll at least start it every two weeks, letting it run some. Yes, I use 100 LL fuel, with some non-ethanol regular mixed in.
The $100 was better than $2k for a new tug, especially with how often it's called into action