Problems playing PSX backups - Please help!

[Crash Bandicoot]

Hi all

I recently dusted off the old PSX (Playstation) for some oldskool gaming. My Playstation has always had problems playing 80% of backups I through at it - no idea why. I burnt a couple of games today - one of them had really shaky FMV sequences then stopped playing shortly afterwards. The other seemed to play fine until I went to start a new game -- the disc would just keep trying to load or stop spinning altogether.

I have an older PSX, '98 I believe. I use a cheat cartridge and tape over the disc sensor button then boot from an original CD in order to play backups. (no internal modchip)

Original games play perfectly, it's only backups that are the problem. I've tried burning to different CDR media and at different speeds but still get the same results. (laggy/shaky FMVs, music cutting out, stopping altogether, etc).

Any help or advice to what could be the problem would be greatly appreiciated!

Thanks!!

(and sorry if this exactly Q has been answered before, I couldn't find anything via Search).