Back about 1995 I bought a used Minelab Sword (original Excalibur) which I still have and use.
The problems I have had to repair were open power cable (twice), leaking O-rings, leaking around control knob tube and the control housing (the tubes were originally glued into the control housing), leaking battery tube (originally the bottom was a second piece which was glued into the main tube, replacement of the battery (first time with Sun-Ray, second time with a MAXXPACK), a minor repair on the headphone speaker hardware and replaced all knobs with brass and stainless steel fastening knobs. The two modifications I made were the addition of the waterproof WOT coil connector and WOT coil and cut the ears on the battery pod to fit the Excalibur 1000. The Sword is still going strong and is packed to go on vacation in a couple of days. I have about 5000 hours in the water with this detector.
About 2002 I bought an Excalibur 1000 as the Sword was down with a bad power cable, I was leaving on a vacation the next day, and no time to repair the Sword.
The problems I have had NO problems to fix on the Excalibur 1000, I have added replacement knobs with brass and stainless steel fastening knobs and replacement of the battery, upgraded the battery to the RNB 3000. I have about 7000 hours in the water with this detector. The Excalibur 1000 is also going strong is packed and is also ready to go on vacation. Vacation for me, hard work for the detectors.
I did not mention a lower shaft that was destroyed when a bus driver in Cancun closed the door before I got the Excalibur into the bus. The general maintenance items such as the spring clips, nuts and bolts, and adding a bit of epoxy PC7 to the inside of the coil ears as they wore and the teardrop shaft washers. I also used Whites dive shaft handle until I went to Carbon Fiber Over and Under travel shaft - only one shaft to pack! Oh yes, I do pack 2 lower shafts.