Presuming, for the moment, that it is, your pump's failure may actually be due to a crack in the hose rather than a failure of the pump head.
If your pump is indeed a floor pump, then you can replace the current hose with a generic hose (e.g., clear "aquarium"-type hose that you can buy at HOME DEPOT ... at least, in my neck of the woods ... the clear hose was/(is?) also used as fuel line on some motorcycles in the past ... I'm just presuming it will withstand 100+ PSI, BTW) + the SILCA pump heads will probably fit 'in' most air pump hoses if you discover that the problem with your pump is actually the hose & you cannot fit your Zefal pump head on the replacement hose.
BTW. The diaphragm within the pump, itself, can sometimes fail ... you can often substitute a piece of medium weight (whatever THAT is!) leather (the material of choice prior to the age of rubber-and-plastic) ... you may have to dampen the leather with some oil.
If your Zefal Husky happens to be a frame pump, then I recommend you simply get a new pump because most of the available replacement parts will undoubtedly cost as much as many new frame pumps cost.