CB11, welcome to TFP!
The tools you'll need to do this are:
9/16" wrench
7/16" wrench (open -or 'box' end)
1/4" nut driver
Silicon or teflon base lube
The seal assembly (SP 1600 Z 2)
Possibly a housing gasket (SP 1600 T)
Perhaps a pair of channel locks to remove the impeller
What you want to do, is use the 9/16" wrench to unbolt the back of the pump housing (some have 4 bolts, some have 6). This allows you to slide the motor and back end of the pump housing out of the main part of the unit. You may have to disconnect the ground wire so you can get the motor end to a place where you can more easily work on it. Now use the 1/4" nutdriver to unscrew the 2 retaining bolts on the back of the motor (they will not come out all the way - there's a stop on them) At this point the end cap on the motor should just slide off (though you may have to use a flat screwdriver and a hammer to knock it off). Once the end cap is off you'll see all the wires, etc. (it's probably a good idea to kill the power to the pump at the breaker
) Now take the 7/16" wrench and CAREFULLY shove it past the capacitor (black cylinder - looks like a C or D cell battery) - DO NOT let the wrench 'arch -out' the posts on the capacitor!!! - you'll get a nasty shock if you do! Lock on to the motor's shaft (the shaft is dead center of the motor and is notched to accommodate the 7/16" wrench) and unscrew the impeller. Make note of how the 2 part seal assembly (SP 1600 Z 2) is oriented and remove it- the metal part goes on the impeller with the raised lip away from the impeller, the ceramic part goes into the sealing plate and has the rubber side towards the motor. (Lube the rubber part of the ceramic piece) Using the 7/16" wrench to 'back up' the shaft, reassemble it ( the seal plate has "TOP" written on the top) and then screw the impeller back on. Check the housing o-ring (still on the pump housing, if it's flat (the o- ring is flat to begin with, but it should protrude ~ 1/32" out of the channel) replace it with a SP 1600 T. Replace the diffuser (it only fits one way onto the seal plate and slide the motor back into the housing and put the bolts back in. When tightening the bolts do NE then SW and NW and then SE - if you have the extra 2 bolts on the sides, do them last - this will apply ~ even pressure on the gasket and prevent pinching so that you don't end up with a housing leak.
This is a quick explanation, if you have any questions - I'll be happy to clarify anything I've said - I've done this same thing 5 times this past week (actually 3 of them were motor replacements, but you've still gotta change the seal assembly when you change the motor 8) )