M-Audio controller. How do I fix a loose sub port?

I just had the same issue. The temporary fix I used worked for 2 years. I just stuck a small paper clip or safety pin in the corner of the port, and then plug the cable in. If those are too big just use something you can use to make the plug fit tight.

It finally stopped worked a couple of weeks ago, so I just bought a new USB port at an electronic store for $1.50 and soldered it on. I had to buy flux which was $3.00.

$5 and an hour of time after squeezing 2 extra years with paper clips. Priceless.

Just make sure you have a cold beer to solder with. Sticking drinks in a freezer wrapped in a wetpaper towel for 15 minutes is like a reverse microwave for beer.