If you are running software 2.4.1[1] or later, the encoder knob can be used to fine-tune any other knob parameter if turned within 2 seconds of turning any knob.
Rough tune with the delay time knob (either Dly time A or B) and then within 2 seconds turn the encoder knob and you can fine tune the delay time 1ms at a time. The encoder works this way with any setting, such as mod depth, FX level, etc…