I haven’t got a service manual for the pedal but it’s not too hard to work out what needs doing from the schematic and any tech worth their salt will be able to work out how to optimally bias them. There’s 3 trimmers, one sets the bias of both halves of the BBD, one sets the gain between BBD’s which in turn provides an equal 50/50 dry and wet mix and the final one balances the output section of the BBD, which is the one you’re probably most interested in as it will remove clock noise (just to clarify, clock noise as in a high pitched constant whine, not hiss or a chirping sound?).

Assuming it’s the constant whine mentioned above, you can probably adjust the balance trimmer yourself if you’d like to avoid a tech, it will be the one marked ‘1k’ just power the pedal on (being careful to keep your hands away from the power switch contacts/transformer section as this carries mains electricity) with nothing plugged in to the input jack, put the edge ‘on’ (the brighter mode) the blend CW (the vibrato side) and adjust it for the least whine, there will be a small section around the middle where the whine gets quieter, tweak it carefully until all the whine is gone.

Hard to say, a lot of “tech’s” will be DIYers who have no idea what they’re doing and will ask on pages like these for help, but there are some experienced folk out there. If you’re in the Americas, contact The EH Man on here.