e-unit issues

[steve1946]

I'm rebuilding an e-unit from a pre-war steamer and I can't get it to function.  It is detached from the motor. I've done the normal functions like clean the plunger, contacts and drum.  Everything looks good, clean and functional except when I try to hot-wire it from the transformer by touching one transformer wire to the e-unit frame and the other to the coil solder lug all I get is sparks.  There is no movement with the drum.  I don't have any testing equipment so everything has to be done by sight.  Does anyone have any suggestions?  Thanks,  Steve

[cwburfle]

Did you disconnect all the wires from the e-unit to the motor assembly, and remove the e-unit? If not, the short could be external to the e-unit.

Check the wire going from the coil to the solder lug. It it touching the metal frame anywhere?
Check the wire running from the solder lug to the e-unit's contact assembly (four finger). It might be touching the frame. Or the contact itself could be touching the frame. Or one of the wires coming from the other contacts might be touching the frame.

Finally, there is a spacer built into each side of the e-unit drum which prevents the copper drum segments from touching the frame. I have seen drums worn to the point where those copper drum segments were rubbing against the metal frame, causing the short.