Originally Posted by f1100turbo
Non fixable to my knowledge.
Welcome to the forum!
You are correct in that the LP Change Over Regulator is not field repairable.
There was a "bad batch" of these devices from Marshall Brass a few years back, and Marshall replaced all that were reported at no cost. Probably too late for that course of action. I shipped boxes (12 per box) of the defective Regulators back to Marshall Brass.
Also, going back a few more years, that change over Regulator "used" to be manufactured with two separate regulators, the First Stage which also contained the change over mechanism, and a Second Stage regulator that connected to the First Stage with a brass nipple. Since a stand alone Second Stage is available separately, people were replacing the Second Stage portion when a diaphragm would fail, but in some cases did not use the correct Second Stage regulator and "accidents" resulted.
Big brother stepped in, and now the Marshall Brass Change Over Regulator is manufactured in one piece, with both the primary (high pressure) and the secondary (low pressure) integrated into one unit.