Had to have marina redo (for dozenth time it seems) some wiring because the connectors they used on the power wires to the hatch lifter failed due to poor installation.

The mechanic said the copper strands in the #8 wires that go from swtich on dash to lifter were "black" and brittle. Recommended re-wiring the entire lifter harness.

At $90/hour I question if it needs done--or if it does I know I can do it for a lot less.

Question is--is this something that needs immediate fix?

Copper oxidation, esp. around salt water is common.
This is commonly exhibited where the copper wire is
exposed such as with the "crimp" connectors. Shrink tube
should be used where ever possible. The oxidized copper
can often reach back under the insulation as you try to strip it back to reveal fresh conductor. This can result in the loss of length of wire and sometimes is intolerable... The black and/or green oxidation can be removed several ways... One quik way is the use of a Muriatic acid dip, followed by a dip in a strong cleaning solution ( such as Castrol purple) then rinse in clean waterand dry with a rag... This sounds funky but it works instantly. The strong soaps (like castrol purple ) generally contain base i.e. sodium metasilcate or potassium hydroxide, this neutralizes the acidic state of the muriatic. The wire ends should be "tinned"with solder ( no flux needed if the acid dip is used. Connections, if under screws, should be sprayed with an ignition or electrical sealer. Good Luck