MGS4 Disc error question mark

Hopefully this can be solved.

I've been playing MGS4 for the first time in a few years the last couple of days, and everything's fine, right up to the credits. the post-production is where it freezes and has a blinking question mark and disc error. I've tried to clean it, using my disc cleaning tool, only, when I did, it wouldn't even load, has a black screen before any cutscene. I've used my shirt to wipe anything and then it would play the scenes. But it still has the error, I've tried it now, after doing the full install option as a shot in the dark.

But I do remember, the last time I played it, on an old ps3, it would freeze on the credits aswell, a few years back. Either I left it and forgot or I fixed it. I don't know if that helps that it's happened before. But only on the credits, nothing else.

TL;DR Disc read error on MGS4 credits, happened before, don't know how to solve. I really don't want to pay £15 for a replacement, as I have also read that that wouldn't even work

That started happening with me when I did the full install. When doing chapter install (deleting previous ones), the game would play normally as always.

So my advice is: delete game data (installed stuff), and re install a new one.