If you have Mylar/Polyester tape (you normally can't see light through it), then you may want to try baking your tape before you play it. There is a glue that binds the oxide to the plastic that can absorb moisture causing it to break down over time. The results, include losing important information off of your tape and also clogging your tape heads and other mechanical parts of your deck. Years ago, it was discovered that baking these tapes at between 130° and 140° F for several hours will reactivate that glue, force out the moisture and give these tapes new life...at least temporarily. There are several sites dedicated to such things and a scan of Google looking for baking tape should get you the specifics you need. This does work miracles and can be repeated, but if you have a bad tape...you should certainly try this before playing and potentially damaging it. This is not recommended for Acetate tapes which were more prevalent in the 60s and before. These tapes appear translucent in light. If you bake them, you'll just have a stinky mess and a ruined tape, so make sure you've got the right thing before firing up the oven.
Most of the individuals pushing this process have recommended ovens...(no gas, no microwave) and specify that you have to have a good regulated temperature and cool down period to insure the success of this process.
Depending on the chemical makeup of your particular reels, you may want to transfer your tape to a metal reel before performing your bakage.