I found a walk in freezer not cooling (routine maintenance). I could feel the liquid solinoid valve was calling. Went to the remote condensing unit a Copeland Discus and found that the Penn 45( lubrication protection had tripped) this is the older mechanical pressure differential. I have to be honest I've never checked the oil pressure before, so I checked the PSID by using old set of gauges. My reading was at peak 68 PSIG. I also found that the contactor was pitted. I am replacing this contactor. Any reason to upgrade the Penn 45 with the electronic whatchamacallit ?