I’ll start with the last question: there isn’t any way to clean the tapes.
Now lets look at some of the causes. Are you using a mixture of brands — e.g., Sony and Panasonic tapes? If you are, this could be the cause of your problem. Tapes have a microscopic layer of lubricant on their surface, different for each manufacturer. Mix tape brands and the lubricants can combine to create “gunk” on the record or play-back heads. It doesn’t matter which brand you use, but don’t mix brands.
My inclination, if this were my problem, would be to take the camera to a repair shop and have it thoroughly cleaned and aligned. It’s possible, for example, that the problem is dirty rollers and guided in the camera rather than gunk on the heads.
And perhaps most importantly, don’t clean the heads again yourself! You should be able to records dozens — perhaps hundreds — of hours between head cleaning. Repeated cleaning can cause undue wear on the heads.
It’s also possible, although less likely, that there is some kind of electrical interference — e.g., a loose or damaged wire or something at fault in your computer. Have you tried playing from your camera to your TV monitor?
Good luck
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