Just a heads up for WE operators.
I found a local source for the nozzle o-ring (part #45). I personally haven't one fail but I like to keep extras handy just in case!!! The only snag is they require a minimum purchase of $25.00. I just bought a metric o-ring set which included 20 of them as well 29 other sizes for $23.00
http://www.globalrubber.com/
The o-ring size is 7mm ID with a cross section of 1.5mm (7mm x 1.5mm)