Did you chew up the head of the screw, or did you strip the thread of the screw in the disk carrier?

If it's the first, avoid filing/cutting the head of the screw unless you have a good way of removing metal filings/dust. I had to clean a player where this had been done without any consideration: it wasn't possible to clean it properly and I couldn't sort it out as a result. The way I have done it in the past is with a Mole grip, overtightened to "clamp" onto the head of the screw at right angles. Careful! If you PM me I should be able to pull together a few spare screws for you.

If it's the second, you will need a new sled mount. I have a few of these, but - as with the rest of the spares - they are buried in a pile, and you will have to be a bit patient for a while until I can get to them again. Sorry!