Man I remember the bad ones. Go to zfdoc.com and/or our zr1netreg site to get the skinny. The seal on backwards was not the only defect on the DOM type slaves cylinders.
seal on backwards.
bad welds @ the line bungs.
various porosity issues with the metal.
Bore run out.
lousey machining of the ends of the springs. The spring end is machined flat and they never chamfered the ground ends, so they broke off after a few cycles.
General metal fragments left behind, Bill felt they came from the tapping of the bungs.
Back in late 05 & early 06 I went thru six sets of masters & slaves before I got one slave to work. Some of the masters had badly formed reserviors, porosity, weld, & metal shavings issues also. I was doing my r&r at the height of the "spillage" issues, so it was a real crap shoot on the parts. I finally had to assemble a slave from parts scavanged from other new deffective slaves and a cast type cylinder. Quality control.
I would suggest if you continue to have trouble to call Bill at zfdoc. For me, that was the most expensive "cheap" thing that I did to my Z.
Tom