Machine Auto Bubbles

I have a Krups XP5020 consumer grade semi-auto Espresso Machine.

I have to say that it is pretty decent but it is still a consumer grade machine.

It has a"fool-proof" milk frother enhancer (warning! warning!).

Anyhow, sometimes (only sometimes), it CAN produce decent microfoam with half and half milk. But lately, it could not foam for nuts. I thought the rubber bung that lets the air in might be stuffed up so I used a needle to clean it. Could not see through the hole so I used a small toothpick. I think it was a mistake. Coz now it foams but it make large bubbles instead of the microfoam I need.

Any ideas on how to fix the problem? Aside from getting a new machine coz I AM working on that.

Thank you.