After 3 years of never having an issue with my Az-Eq 5 the last two night have been user error heaven. First night about half way through a run in Cygnus the scope (I change from my 4" to 8" ) the scope hit my Velcro attached GPS for about 3 seconds. Did a lot of 5-6minutes EAA in Cygnus and everything was still good. Went to Cassiopeia and everything went south, could not even get a 1 second image. Tried again last night and the same thing. Seriously worried now. Then this morning I went out to try and figure out what was happening. Well I found the error and it was certainly user error. I have two different marks on the mounting rail for the C8 (EQ and guide scope take a significantly different rail location). I forgot that I had the AZ mark toward the front part of the rail, the C8 was extremely poorly balanced toward the back of the scope, no wonder the mount could not correct at high altitudes. When I released the axis break the scope immediately rotated 90% skyward.
Only one good thing (besides understanding that I need to think through each way I setup the mount with the various scopes/setups I use and not go on "autopilot") is that I learned that my new lithium power station (300W) is an amazing addition. During last night attempts my first laptop battery died. I put in the spare and it only had 30% charge. So I got my AC laptop power supply and plugged it into one of the AC outlets (charging and running the laptop took 45 watts). The power station reported I had 7.5 hours of use left......Wow, expensive but worth it.
EAA is significantly easier than AP, but even simple things like scope balance can bring EAA heart break:)