My dryer was not drying loads completely, either on timer or moisture indicator. The ducts below the lint screen tray were clogged with lint. Next time you are in the guts, you might check for buildup. Also, I understand that use of dryer sheets can cause the lint screen tray to look fine but actually be clogged, preventing good air circulation. Run some water into the tray - if it doesn't drain through, scrub it with sudsy water. I have heard that this issue can cause fires. And good luck with your repair!