you use a cardboard isolates triangle for the sensor flip underneath the disk.
Then you put a piece of cotton ball in the little hole on the right of the ps2 unit where the tray closes down.
then you take the ps2 apart and tape down that final button and make sure it wont come up.
food for thought: you need Tony Hawks ProSkater 2. Its THE PS1 host disk used for Disk swapping and its the biggest in file size. If your host PS1 disk is smaller in file size than the burned game. it will be a mismatch and will NOT load or give you game breaking problems.
source: did this myself and works completely fine. until the lovely Temp here helped me hack my ps3
years ago, also I did this method via the PS1 and It worked almost nill to none and is very obscure method. Requiring 4 SWAPS. Requiring a disk swap when the motor slowed down, then showed the PS logo and the words disappeared and if you didn't have perfect timing the game would skip or sound would be missing ....ahh good times...
Kinda awesome someone else besides me knows about this awesome obscure trick for the PS2.
ANYWAY (i digress) as to regards to your problem. You may have touched the eye or the part that holds the disk. and MAY have pushed it out of alignment. Also, I would have avoided glue as that shit can residue and go onto the motherboard and other places you wouldn't like for it to go. Not saying that is your case here, but it could be likely. I would open the PS2 again and see if all connections are tight and check if any glue is on the board
also moar fewd for thought: In order to swap you have to
strain the disk motor most of the time taking the disk out and swapping when the motor slows down for the "check"
although convenient, this method
will shorten your PS2 Slims motor drive life.
I DIDN'T USE FMCB