When you say grip do you mean just get hard to turn? On my 54 I was about to remove and replace my handle. It was hard to turn and the tank would not empty, I thought it was the handle, it was sticky but it ended up being a build up of scale in the drain pipe. I put descaling liquid in (Harpic 10) that loosened the build up. In the end I got in the tender, used an old piece of 3/8 inch dowel/stick and ran it up the hole from the waterline, it broke the scaling and drained, now it turns easy and the tank drains properly. Re and re the valve could be a messy job.

Virus-free. www.avg.com