Hi!
This summer I had the same wish (new sender for oil pressure). The instrument, normally, indicated correct pressure at cold start but after the engine got warmer the indication was mostly zero with a few moments of correct indication. Two weeks ago I was lifting off the cable lug to do another (of many) tests to be really sure that it was a faulty sender.
When I lifted, the cable broke off at the end of the plastic cover (se picture).
This picture indicates that the copper had broken “under” the plastic insulation and this, sure, did not happen in one day…
I can also inform that this cable, recently, “passed” a connection test, giving a solid 11,5 V to earth (engine off and ignition on).
After a new cable end and a new cable lug, the instrument works very well.
I do not expect this information to solve every problem but it can be helpful to see that a, visually, sound cable can hide some, hard to find, problems.
Best Regards: Göran Olsson