While I can't speak of the Nelson 6000 in particular, when it comes to irrigation equipment, my experience in this forum generally indicates that if a component (valve, sprinkler head, etc) has a problem and it cost less than about $20 to buy a whole new component, you're typically better off buying the whole component than trying to buy replacement parts. The replacement parts tend to be nearly as expensive as the whole component; then, and repairs can be easier as rather than trying to replace a single part, frequently you can replace the guts without having to remove the part of the equipement attachted to the rest of the irrigation system.