Jim - That is a positive ground SU pump. Whether or not it is the correct one for the MGB, I can't tell without seeing the rest of the pump, but I will assume that it is. You can probably get the pump to run for you by just cleaning the points real well. You will need to remove the spring blade with the upper contacts, by loosening the screw at the back and then scrub the points really well on a fine sharpening stone or some 400 grit sand paper backed on a flat piece of steel or glass. To clean the lower set of contacts, remove the two pedestal mounting screws and carefully rotate the pedestal back around the pivot pin that attaches the lower toggle to the pedestal to fully expose the lower contacts. Scrub the lower contacts well the same as was done for the upper contacts. Reassemble the pump and it should run fine. Now for the kicker, if you set the pump aside to use when the installed pump dies, it probably won't work for the same reason that is is not working now - the points develop a film on the contacts over time and depends on the current through the points and the arcing to burn the film off. On a pump that sits on the shelf or in the trunk as a back up pump, this film just sits there, getting thicker as time goes by with nothing to burn it off and before long the contacts are insulated from on another and the pump won't work. I can convert the pump to solid state for you if you want to use it as a back up pump, or you can purchase a Facet pump from NAPA and install it as a permanently installed back up pump (see the article, Backup Fuel Pump in the SU Fuel Pump Articles section of my web site at: http://homepages.donobi.net/sufuelpumps/) and send me the original pump when it wears out.
Cheers,
