Just in case someone else runs into this problem, compatible capacitors can be found on ebay and other places but they are not exactly the same as the original. That's OK, they don't have to be.
The original for the 250 gph pump I have is a: CBB 61 package type
It's rated for: 250 Volts AC
The capacitance is: 16 uf (microfarads)
It also has 4 terminals.
"CBB 61" refers to the general shape although not necessarily the exact same size. You don't absolutely have to have the same size but it can't be too much bigger or it won't fit in the housing.
The replacement should have the same voltage rating OR HIGHER.
The capacitance rating must me the same (16 uf in my case)
Number of Terminals? This where I got stuck. The original has 4 and I couldn't find any of the CBB 61 package type that had the proper rating and 4 terminals. I was all set to order a larger can type and hope it would fit when I decided to do a little more research.
It turns out that while a capacitor might have several sets of terminals, most only have two "poles". Multiple terminals are connected to each pole to all allow for several connections. In the case of the original pump capacitor, there are essentialy two pairs of terminals, where each pair is connected to one of the two poles.
Once you realize this, then you'll discover that there's actually quite a few capacitors available on ebay and other places that will work. An expensive two wire capacitor like the one I got is just fine. You can cut off the 1/4 inch quick disconnects in the pump and just use wire nuts if you want. If you do this, you'll end up with two wires from the pump connected to one wire of the capacitor and one wire from the pump connected to the other wire of the capacitor.
I spent about $3.00 at Radio Shack and got the male ends of the disconnects which I attached to the wires of the capacitor, - two on one wire, and one on the other. So for about $13 (the capacitor was $10 including shipping) I've got a working pump again.
One other comment. The capacitor I found was rated for 450 Volts, which again is just fine. However it was slightly bigger than the original and the hole for the mounting bolt didn't line up right. So I just used some duct tape to hold the capacitor in place while I put the housing cover back on. There was plenty of room for it.