Thanks John. I will take a closer look tomorrow but don't like the sound of that 'inside the head'! Does the head have to be removed to replace that 'o'ring?

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'87 BMW 325 convertible (162k + miles)
'87 300E, 144k + miles (sold)
'93 Chevy Blazer (full size), 207K + miles
'89 Sea Ray 390EC, 2 x 454's, 1550 hours...
'85 AMF Sunfish

Olde Towne Portsmouth, VA