Well, I decided that I needed to reset things as the delay side was producing a loud tick which was both speed-adjustable and very annoying.
I turned both trim pots anti-clockwise until they clicked and then counted spins of my screwdriver before they clicked the other end, which was around 50.
I returned them both back to the beginning (fully anti-clockwise) and then made twenty turns clockwise to each. This left things sounding a little sparse and tame, so I've just turned both ten turns anti-clockwise and it now sounds much more pleasing (weird).
As long as I don't encounter more unwanted noises I'm going to leave the trim pots alone and start recording some new stuff