1977 Westerbeke M30 oil pressure sender.

[maurice]

A few days ago, the oil pressure gauge on my 1977 Westerbeke M30 appeared to give a false low reading. There was no shortage of oil and a day later was back to normal pressure. In a 1976 Service Bulletin, Westerbeke gives a guide to checking the gauge and sender. Fine for the gauge but neither I nor a friend can find the location of the sender. Would very much appreciate any advice.
Thanks
Maurice

[Straebel]

A loose mounting bracket caused my sender to give a false low reading (no pressure) several years ago.