Loophole - Motor boat sound

[kev77]

Loophole  - Motor boat sound,
hi all - gots me a looper that makes a fast put put put motorboating sound in the playback signal.
any quick ideas about where to look?
records good - dials are responsive, LEDs work - play back is clear - BUT
has the additional sound,.,.
which just makes it unuseable

[kev77]

is this a common issue? I def didnt hear it in the online demos