I use a dry paint brush to clean the bobbin area whenever I change it. I don't think the quilt is too tight. It's got a little looseness in it and is loaded the way my dealer taught me to load them. I have a take up bar so I don't have to lift the back bar.
My dealer came out and fixed the machine recently because something else was wrong with it. He checked everything then so I doubt the spring on the disk is a problem. It is threaded correctly. I always double check that because that was a mistake I made more than once when I first got the machine.