Bubble Magnus Doser problems

[okseeme]

Have anyone experience their BM go off without the power going out! Sometimes when I get home my BM is completely off with no lights on! Only thing that shuts down. I unplug it n plug back in and it works great again for couple days than completely shut off? It sits about 7 inches up and behind my sump. I heard moisture may cause it but I put a fan on it so not sure why any moisture would affect it! I want to put outside my stand but not sure what's the longest I can have the tube line for it to properly pump! Any advises would be greatly appreciated