Naj,
The new style pump like yours is a simple matter to rebuild providing the communtator on the armature is not that far gone. As pointed out, the biggest problem is usually encountered in disassembling because the screws tend to rust up so bad. This isn't quite the problem on the newer pumps as it was on the older, large style pumps which are a little more difficult to rebuild but certainly can be. With the newer pumps, I usually take them completely apart, cleaning thoroughly.
These are "wet" pumps and the brushes and armature "ride" in the gasoline, so if the gasoline has been sitting in the pump for sometime, it tends to congeal with the carbon brush dust to from a paste that gums up the brushes in their holders. When you remove the armature make sure you note the number of shims under the e-clip that holds the armature in--you'll need to replace these exactly. There most like will be a set of shims on the opposite side i.e. inside the area where the bushes are mounted. Once apart give the armature a good cleaning with electric contact cleaner/degreaser. Find youself some very fine sandpaper (#3000 or more) and polish up the commutator until it is a shiny copper color. If the com is really "tracked", I'd use some rougher paper to turn the comm preferably with the armature mounted either in a lathe or good drill press.
The brushes are fairly staightforward to remove with a desoldering tool and replace with a dab of solder--this is the easiest part of the job. Clean out the "can", find youself some new rubber o-rings of the correct size and re-assemble. Before re-assembling the whole pump, you may want to just reassemble the motor part and "run" the new brushes in by connecting up to some 12 volt power source and letting the motor run for a while. It also helps to periodically reverse the leads to let the brushes wear in during this short "run in period".
First thing you'll need to do once assembled is to make yourself a little test device out of an old bucket and some hoses so you can conect up and test for leaks. I usually do this with some diesel fuel because it's afer and I'm a "scarey cat" around gasoline and sparks. You don't want to find out you have leaks after you go through the pain of re-installing the pump. This is a real easy job to do. If anyone needs similar advice on how to approach the older pumps let me know--I've done about 10 of them with real good results. Good luck
George Des
