What would cause a Mag 12 pump to intermittently not want to start up. It will work fine for several days on a pond for circulating a falls. I'll turn it off to clean the filter and it may or may not start back up. Tap it with a hammer and it may return to operation. Taking it off line and taking it apart and reassembling it will always make it ok for a few more restarts.
Id like to put the pump on a timer with half hour intervals of non operation during the night hours to cut back on electric usage, but am afraid the pump may not restart each time. Thanks in advance.
It sounds like goop around the impeller magnet. Grab some q-tips and clean the impeller itself, and the hole it fits in on the pump. If you pull a bunch of grunge out, you just found your problem! Just periodic maintenance that needs to be done with those.
Mag 12 Pump issue 
Linear Mode
