Learn from a pro on how to maintain VHS tape. Often times, old VHS tapes have both mechanical and electrical issues.
I come across this youtube channel that share his experience on cleaning and maintaining old VHS tapes.
Fix the mechanical issues first before the much tougher electrical issues.

3 Ways to Clean a VHS Tape - Mold Removal ** Tape to Digital Conversion in Pensacola, FL
https://www.youtube.com/watch?v=PfIJBpn1ymY

VHS TAPES - Common Issues Digitizing and How to Fix **Tape to digital Conversion Pensacola Florida
https://www.youtube.com/watch?v=GkFRidiFwBg