I am fixing up an espresso machine I bought on craigslist. It has a procon rotary pump. The valve on the side of the pump had a lot of scale built up on it. I de-scaled and now when I activate the pump there is a slow leak from the valve. I can't find anywhere online where I can buy a replacement. Any ideas?

Did you replace the o-ring on the stem of that valve?

I thought that it had a plastic valve seat rather than an o-ring. In any case I haven't been able to find any replacement parts for it.