The encoders on the Waldorf Blofeld have a long history of going bad. Waldorf sells a kit to replace them but were out of stock at the time I needed them. They helpfully list the specs but in the event they stop providing them I’ve copied them here with the part numbers I ordered from Mouser.
6x Bourns PEC16-4020F-N0024
- 16mm encoder without detent
- 24 PPR
- 6mm D shaft
- 20mm shaft length
1x Bourns PEC16-4220F-N0024
- 16mm encoder with detent
- 24 PPR
- 6mm D shaft
- 20mm shaft length
There’s also the 10k linear potentiometer for volume, same shaft specs as above but a 12mm body. Bourns PTV111-3420A-B103 should be a suitable replacement.