1999 Monaco Windsor oil pressure gauge

I'm having trouble with my oil press gauge reading erratic. It seams ok at lower rpms but at around 1600 rpms it starts reading high. sometimes pegging the gauge at 120 psi. I can't locate a replacement sender its a 0-120 gauge made by Teleflex. I called Cummins and Monaco they were no help. I'm trying to find a site for the gauge manufacturer Teleflex. The sender is a normal looking bell design with 2 wire studs on top. Thanks in advance for the help. Robbie