"Fixing itself" after a bit can also be due to sub-par/failing capacitors working better after warming up a bit, though head clogging is of course also a possibility yeah.
Judging by the service manual, VEP03895D (VEP03895C in the SM, maybe there were multiple revisions) is the sub luminance & chrominance pack, responsible for noise reduction and Y/C separation. So, bad caps there could certainly cause image distortion.
Not very familiar with the 1970, but the relatively popular PAL NV-FS88/FS200 decks are based on the same layout and share like 90% of the parts, and they do have certain caps that go bad on the equivalent board. The specific module (they're called a Hybrid IC typically) in the picture seems to be for Y/C separation or something, and the video signal goes through it both on playback and recording, so if the caps go bad it will cause issues. That module/hybrid IC in particular differs from the PAL equivalents (on the FS88/200 there is a different module in that part where the caps go bad), though I did find
this random post about someone replacing caps on the same sub-module on a related japanese deck. Might be easier to replace the caps with new SMD ones though given the space constraints rather than what that person did.
I've replaced some SMD electrolytics on a NV-F77 (the non-svhs top of the line deck from the same lineup as the FS88/FS200, which shares most of the parts except the video circuitry) on a hybrid ic/module:
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I just used hand-soldering and solder wick rather than using rework station/hot air, but that might be a better solution, I'm no expert. If you've never worked with SMD electrolytics before it might be a good idea to practice on something else first though.
Another thing that can cause static/noise looking a bit like head clog/massive dropout on these early/mid 90s panasonics (or at least the PAL variants) is bad/cracked solder joins on the video head assembly as shown in
this video, so that may also be worth checking if you experience similar symptoms.
Bad Power supply capacitors can also be a thing in decks of this vintage, though that tends to cause more subtle waves or noise on the image due to ripple/instability of the voltage going to the circuitry, or alternatively trouble turning on.