I have a Samsung DVD-V6800 VCR/DVD combo and a Sony SLV-SX70 VCR. The samsung doesn't play tapes very well and i don't know why. But when i record onto a tape with the Samsung, the Samsung plays it back very well! But if i record something onto a tape with the Sony (or any other VCR), the Samsung doesn't play it too well but the Sony does! (Except with my Samsung)!
As far as i know, both of the VCR's are recording in PAL!
How you can fix it is not a simple question, look up some service manuals or guides, and open it up and adjust things if needed. Finding a VCR repair tech these days is probably as easy as finding a telephone switch operator.