Full recap
Every electrolytic capacitor replaced with new parts, board cleaned, and any damage from leaking capacitors repaired.
Electrolytic capacitors dry out and leak. On anything from the 80s or 90s this is less a repair than a service item that is thirty years overdue, and leaking electrolyte will eat traces if it is left.
Price depends on the board and the count. Compact handhelds and small audio boards sit at the lower end; large multi-board systems cost more.