It's been several months since we last turned the 3-way valve that controls whether the filter is getting input from the cleaner line, skimmer line, or both (these lines were re-done last year when we had the pool resurfaced). And the other day when we tried to set it so that it was getting input from the cleaner line only, it seemed that it wouldn't turn to that position (so our 3-way valve seemed to be acting more like a 2-way valve - input from skimmer and cleaner lines or input from just skimmer) - could've sworn that we were able to do that *last* season but we didn't want to force it and break it. Is it common for these valves to get stuck? Are there any hints/tips for un-sticking them and any online diagrams? Will try to take a photo tomorrow. Thanks!