Gresp15C

Mine is similar, but with a black base of a slightly different design. The base has a crack, probably related to the chemical damage, and will probably let go someday but won't affect how the pump functions.

The pump came with an impressive looking convertible presta/schrader chuck that I must admit is too futzy for my use, or I'm just incompetent. Even with a new silicon gasket. So I replaced it with an even older threaded Schrader head and Presta adapter. It's not as quick, but extremely simple and works every time. We still have a few Schrader bikes in the family fleet, so I need to support both types.

luns

I think the crimp was factory, but didn't exist for all years. The pintle (Spillo as Silca called it, simply italian for Pin) was provided by an outside machine shop, as was the cap. They may have had the vendor provide everything assembled with the crimp to make for quicker assembly. The Spillo for these years had a foot at the cap end for this retention.

I've seen this in pumps from the late '80s. I think I've seen pumps from the '90s do away with the crimp but the spillo still had the foot, while pumps I've seen from the '00s as well as '70's and earlier have not had that foot on the spillo at all. I imagine the uncrimped '90s pumps were using up inventory of the old parts after deciding to not bother with the crimps.

merziac

A Q-tip with a smidge of vaseline in the presta chucks really smooths things out on the 3 I have done.