Just a thought, but if it's faulty capacitors in the rack power circuits, then anyone who can use a soldering iron can probably swap them for you. Someone with experience in audio repair will be able to work out which ones to change without any diagrams, just from where they are on the circuit boards. They will very likely be a standard types. It's possible the original ones had too low a voltage rating, so I'd fit the next higher rating available. For example, on a 15volt supply they installed 16volt types - get 25volt.