pedal works on 9v battery but not power adapter

[(DEAD)fx]

So i recently accidentally plugged a reversed polarity power adapter into my Tube Screamer clone pedal, which messed up the polarity protection diode and damaged the IC. So I removed the diode which is optional having in the circuit anyway, and I swapped the opamp for a new one ..... the pedal now works completely fine again using a 9v battery, but will not work when I plug in a standard boss 9v power supply. This seems strange. I did measure the power adapter connector terminals with a multimeter though and was not getting a 9v voltage, more around a couple hundred millivolts. Any ideas on why this would have happened? Or what I could do to solve the issue. I don't really understand how I could have damaged the power adapter in any way in the process. hm

[(DEAD)fx]

haha just got a laugh out of seeing my position/title under my username on this forum is diode destroyer. Which I have now officially earned my title and made legitimate. oh the irony