Just the normal types of maintenance and connections. Clean the tape pick up heads on the VHS. Your manual probably has directions. You may need to demagnitizee. Be careful.
Make sure that all connections are clean and tight.
Make sure that the video grabber device has the latest drivers (if applicable).
Since those tapes are not replaceable, you may want to take them to have them professionably repaired. In fact, you may want them to be professanally copied to a DVD.
Have faith, I have been able to copy 25 year old tapes to a DVD but it did take some time.
Also perhaps others may have a better or alternative solution to that error.
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BoilerPlate: To posters who ask for help -- it is nice to thank the volunteers who try to answer your questions !
Anything I post unless stated with a reference is my personal opinion.