I used an old bottle I had around. It is 91% Isopropyl I've had it so long I think the price tag on it was something like 45¢! Can't really remember what I used the last time. Don't think it was alcohol but some other cleaner. The alcohol did a pretty good job and didn't require as much work as I remember when I did my L80Ts.
I actually used 3M adhesive remover for the rotted foam plug in the 2425J. Didn't try it on the 2122H, for some reason.