The Laserwriter Select 310 printer jams when feeding #10 envelopes from the "Lower Cassette". It has worked fine for about 3 years. I cleaned the rollers just above the envelopes with denatured alcohol, but this has not helped. The envelopes just begin to come out of the tray, up about 1/4 of the way out and then the printer jams.
I was having jamming problems with the upper cassette 6 months ago,but cleaning the feeding rollers seemed to fix the problem.