Long Slide Speed Equalisation Switch for Revox A77, B77 & PR99
These slide switches are pretty vulnerable items. Usually if there is no mechanical damage they can be carefully cleaned with non residue switch contact cleaner and a cotton bud [never sprayed!!]. However sometimes some of the leaves are bent or badly tarnished resulting in spurious speed selection, incorrect equalisation and puzzling poor performance during set up. Because getting to this switch is a major exercise which could be very frustrating if you try to repair it, here is an alternative solution - replace it.
Two types are available for the A77 and B77/PR99 - they look the same but are different on closer examination with different number and position of contacts / leaves.