Well The video and audio is on the same board and that board (picture please?) is usually either the very top board of the VCR or the very bottom board it all depends on where the RCA jacks are on the VCR (Are they on the top side of the back or the bottom side of the back?) Anyways usually with the Panasonic/Matsushida built VCRs (Panasonic or Quasar like yours) has each circuit marked (e.g. Power Circuit Ref. No. 1000) and in the case of the video circuit its more than likely gonna be marked on the board Video Circuit Ref. No. XXXX and the sound circuits are gonna be marked Audio Circuit Ref. No. XXXX.
And those circuit markings should be pretty easy to spot as its etched onto the board in white circuit board ink with the words "Audio Circuit Ref. No. XXXX" (the "X's" represent numbers that would be on the label) is surrounded by a rectangle and the same goes for the video circuit.
I hope this helps.