Chuck,

I recently purchased some of those from:

Mark Fruehauf                    
BALCEN             .                
120 Exchange St. STE 300        
Portland, ME 04101
207 522 6737  Tel
info@...
www.balcen.com

They ship worldwide.  

Item# 007-001

Desc: SERTO – SO 21121

$8.64 ea.

These do thread into the end-caps and have very delicate threads. Do not over-tighten. You need to remove the water-maker tubes from the holder for replacement.

With best regards,

Mark

Skipper

Sailing Vessel - Cream Puff - SM2K - #275

Currently cruising - Vista Mar, Panama

www.creampuff.us

Greetings All,
I developed a leak on the low pressure product water side of the watermaker membrane. It appears to be coming from the gray attachment piece fit directly into the end cap. I tried to tighten assuming it is threaded in. I can't see it as it would require dropping the membrane out of its holder. I am not on the boat now but would like to bring the part back with me. Does anyone know if it does thread in and is it a replacement part?  PA this is not on the bobbin side. Thanks for your time. 
Chuck 
Joy #388
Trinidad