Brake cleaner or acetone. But rubbing alcohol is better than nothing. Most important thing is using all the red loctite on the barrel threads. The set screws are NOT meant to be the main thing securing the comp. That's why people strip them. They over tighten them and use tons of blue locite thinking that's the main thing securing the comp. It isn't.
You could literally not install the set screws at all and the comp will never come loose if your threads were properly cleaned and you sued enough red locitie.
When ready to remove, simply heat it with an open flame (even a cigarette lighter is sufficient) for 10-15 seconds. That will heat the red loctite enough for the comp to screw right off without damaging it at all. Also, the comp basically never has to be removed. For cleaning - simply push the barrel through the front the slide with the comp still on. You can clean the bore, breach face, etc without ever removing the comp.
Long story short:
- Ensure barrel threads are 100% clean
- Use ALL red loctite we include on barrel threads
- Do NOT over apply blue locite to set screws (You can use NONE actually.)
- Do NOT over tighten set screws
One of my personal P-09's has had one of the very first 07/09 comps we ever made on it for almost 6,000 rounds now. I never even installed the set screws and the comp has never came loose.