Are you having problems with the Park pump bodies themselves or just the heads? I've had great service from a Park PFP-4 but OI agree that the OEM head is tricky and unreliable. I refitted mine with the absurdly expensive but wonderful Hirame Presta-only head which, of course, is completely unrealistic for a Co-Op. Ultraman's recommendation for the Silca pump head equally unrealistic since you need both Schrader and Presta ability.

Basically, buy a six-pack of plastic dual fitting heads and plan on replacing them often.

BTW. if you can find any Meidai Top pumps, now long out of production, they are the most durable ones made. An occasional plunger gasket and they will last forever.