Since the remote works for most functions, I will assume that the IR receiver is working on the VCR. I would suspect that the problem here resides on the remote itself. I can’t find too much info on this model nor its remote, but the behavior you describe points to a remote failure. I would open up the remote and clean all of the buttons. These work by shorting exposed traces on the board. There are conductive pads under each button for this purpose. It is possible that either these pads have deteriorated or that the traces have become corroded. Burnish the traces too.
Also, insure that you have new batteries installed. Update this after cleaning/burnishing the remote.
Dan