Ford Transit MK3 oil pressure switch leak

[dan.f]

Hi all, the copper seal on the oil pressure switch of my Ford Transit 100 (1988) has perforated so I am loosing lots of oil. I cannot seem to find the replacement part anywhere, I have been through three different switches recommended by ford for my Reg but the thread is either too wide or the sensor doesn't fit. The part I need is 7994180. Does anyone have any advice on where I could source the part or what alternatives I have?
Thanks a lot,
Dan

[derv23]

Hi , have you tried replacing the copper washer on original switch, if you got and still works otherwise. Nut n bolt shop should have an array of copper washers.

[gotgcoalman]

thought they were a tapered thread?????