The DRZ hadn't hydrolocked again, so I put the rest of the fuel in the gas tank and left it to see if I've finally fixed the problem.
Chris had suggested going flying, so we threw everything in the van and headed to Lincoln, where the visibility was bugger all due to low clouds. Chris had taken off from Placerville, hoping it would get better, but it didn't, so he went to Auburn to wait for a bit. I finished up a bit of safety wiring, then got the plane out and warmed it up so I could start running in the new pre-rotator belts. Imagine me sitting in front of the hangar running the rotor up and down for 15 minutes or so. When I wasn't getting the bendix engaging any more, I stopped the engine and texted Chris to say it was starting to brighten up. He left Auburn, and we waxed the rotors while waiting, but he gave up as the low cloud we'd been seeing was heading towards him. We took the plane out for a couple of circuits, and the first one had the bendix engaging a bit, but the second one was much better. We were pretty close to clouds, so we stopped and put the plane away and headed to lunch. Of course it was glorious when we left the restaurant, but headed home.
The DRZ doesn't seem to be hydrolocked again yet. I'm still leery about draining the oil and putting everything back together just yet, but this does seem promising.