maybe old stock that's "stiffened up"? [doubt they're big sellers!] .... have you opened one? the single action pump here didn't push much at first and didn't make a sound - I banged the push arm down on the bench and it smartened right up, moved well and sounded good - the double one came apart easily and worked fine once back together

I just can't see that diaphragm with maybe half inch around the center metal plate moving much at best, might just be too stiff for manual movement .... but I'd be reluctent to use it too without hearing the nice squishy sound first

Bill


Moved over to the Passing Lane

"When we tug a single thing in nature, we find it attached to the rest of the world" ~ John Muir
"When we tug a single thing on an old truck, we find it falls off" ~ me
Some TF series details & TF heater pics