I suspect that one of the two is defective, and that its defect is more noticeably manifested in one position in the circuit (most likely the the IC1A gain stage, I would think) than the other. Since TL072 op amps are quite inexpensive (BYOC sells them for a buck, though they show as out of stock at the moment), I would just pick up a replacement and try it in each of the IC positions. Hopefully the fizz disappears with one of the two substitutions.
Incidentally, you don't have to use a TL072, since any general purpose dual op amp should work in that service. So if you have another pedal on hand with a socketed dual op amp (JRC4558D, RP4558P, NE5532, TL082, OPA2134A, etc.) in it, you can pull it out and try the same substitution experiment I've suggested. And if my theory that one of the two TL072's is bad is confirmed, I'm sure that BYOC would provide a replacement to you free of charge. Just contact
sales@buildyourownclone.com.
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