The fix is fairly simple but you should consider getting your cassette converted to digital format to preserve it for long term use.
One of the most common cassette tape failures that we have found is the pressure pad falling off. The glue that hold the felt pad onto the spring just dries out over time and then the slightest bump causes the pad to fall off. The easy fix is to carefully glue the pad back onto the spring with some type of super glue.
First find the cassette pressure pad that is typically loose just behind the tape in the housing.
Now; have your cassette tape converted to digital format before it completely gives up the ghost. Let us know if we can help!