I have been repairing SDD3000s for over 30 years.
I repair SDD3000 units and carry a full inventory of spare parts.
But no Knobs!
I offer a Unlimited tech support by email for those who wish to DIY. $150
SDD3000 repairs average $400 but can be more depending on condition.
I offer full universal voltage power supply replacement
I also have repaired units in stock for sale