To minimize problems at the field I have an electric AND a manual pump on my field box. They are plumbed together with a couple of "T" connectors. I use a clip clothspin to crimp the line on the one I do not want to use.

The primary problem I have had with electric pumps is the gear comes loose on the motor shaft. It is not a big deal to fix, but a bit pf a pain to correct at the field since I don't carry any alcohol in the flight box to clean the gear and motor shaft.