Here's a simple quick and cheap fix for a tired pump seal.
Get an old flip flop and mark out a circle on it around the base of the pump then cut it out with some good sissors just slightly bigger than the barrel, then make a hole in the middle of it with a screw driver so the rod can go through it.
As for washers I just use stainless steel washers top and bottom slightly smaller than the barrel of course lol.
If the flip flop is a thin one use two pieces together !
I do this all the time and it works great, takes 5 minutes costs pennies.
I'd be interested in anyone else's methods ?