I'm no VCR export but I have fixed some here are some tips that might help.
1 clean the mode switch it can cause the symptom your having
2 the belt may be bad
3 it could be take and supply hubs but not likely
If it's none of the above it's probably not fixable
You will have to open the TV up and combo units are very hard to work
. Here is YouTube video of Emerson tv/VCR combo that has a similar problem it is long and not all of the video is about the VCR protion but the video might help you fix your TV/VCR combo
https://youtu.be/P4OSlRaVH3g