DieselDave - my advise get it back then refund immediately regardless of what you find.
Never give a customer permission to modify or change anything. I received a MS660 a couple years ago that needed tuned, I sent a message through Ebay asking if it was cool to tune it or have my dealer tune it for me. It was described as running great and ran like crap. He never responded so I returned it through Ebay. Guys here on AS thought I was a D'bag for returning it, but as soon as you change anything without permission it is like licking the top of a cupcake it is yours permanently.
You cannot specify any terms or conditions on Ebay, they have their own rules PERIOD.
"for parts or repair" and "used" are Ebay specifics that drastically change the recourse of a buyer, by selling on Ebay you agree to their law above all others, the real world does not enter into it, unless you believe you have more money to pay lawyers than Ebay does.
This is a real world case of why it is important to bite the bullet as a seller OR not sell used items.
As you sell on Ebay and eventually sell a decent volume your feedback score actually matters, not just as what a buyer sees but as a way of getting paid.
Hypothetically you pay 2000.00 a month in Ebay fees, but you have great feedback with no complaints that have been filed for official handling by Ebay - now you get a $400.00 discount on those fees.
So assuming you know what your product really costs including Ebay and Paypal fees and packaging and postage, you just got $400 FREE.
Now if you lose that nice rating and lose the discount for three months while you get enough new positive scores to adjust your average, not refunding the transaction costs you $1200.00. I only have one saw I am asking $1200.00 for and it sure ain't on Ebay
It's big picture, if you are just selling one saw now and then, that's a yard sale, you will be better off using CL most likely.
For me I never balk at a customer, is it late?
ship a new one
Is it damaged?
ship a new one
Do I suspect they blew it up?
I ask for a picture for warranty purposes, ship a new one and block them as a buyer so I never have to deal with them again.
If they tell me they blew it up I offer a discount on a replacement and DO NOT block them, heck I will even troubleshoot over the phone so they can fix whatever they did wrong.
Letters to Ebay are useless, they are the whole game, if you want to play... it's Ebay, love it or hate it.
DDave