Sony Handycam DCR-HC21 NTSC Audio Problems/ Skipping

Hi all, I have a Sony Handycam DCR-HC21 NTSC Camcorder. It takes Mini digital video cassettes, 60 minutes with a long play option of 90. I haven’t been using my recorder for about a year and turned on some old videos to realize the sound was shot. The video was great, but the audio kept skipping bad. Every second or two, the sound comes in and out abrubtly. I was told it may be heat related. I opened the cover to find minor warping. I was wondering how this can be solved?