How to fix playback issues with VCR that refuses to play EP tapes?

[WCV82]

So now I have two JVC VHS VCRs, both have severe issues with playback on tapes that were recorded in EP format. Sound comes through clearly, but there is practically no picture, just a white flicker on a black screen. However, tapes recorded in SP playback perfectly.

I've manually cleaned the heads on both VCRs using a white piece of printer paper in the methods shown in a couple of different Youtube videos, basically manually moving the playback head and letting it lightly brush against the paper. Each time I cleaned them I got some black gunk off on the paper. For awhile the cleaning seemed to work but after 3 or 4 hours of playing EP tapes, the prior playback issue started again.

Is there another method of cleaning these heads or are the heads totally shot for EP playback? I assume at that point the only solution is head replacement but maybe I am wrong?