On 07/04/2014 15:42, Thomas Prufer wrote:
On Mon, 07 Apr 2014 14:45:50 +0100, newshound
wrote:

If you are *sure* the hose is OK (leak test with soapy water spray?) it
could be the main piston seal. WD40 might let you do a quick check as
you describe but someone will be along in a minute telling you that
mineral oils are bad for rubber tyres. Silicone oil (as used for
lubricating plumbing fittings) would be OK, but not cheap.

Mineral oils are bad for rubber.

Now that that part is done: Grease or petroleum jelly/vaseline on the
leather.That wil stay there, the WD-40 will run off (and also evaporate
eventually). Open the pump, pull out the leather cup thing, dredge the gob of
grease out of the cup and spread it around the rim of the leather, reinstall the
leather with a twisting motion, and you're done (except for getting dirty grease
of your fingers and the new trousers you wore by mistake).


Thomas Prufer

Except that as the OP pointed out, the cylinder is welded closed.

What a WD40 test tells you is whether the pump might be fixable (e.g. by
pouring in some expensive silicone) or whether it is ready for the
scrap-heap. The amount of mineral oil in a few sprays of WD40 is not
going to bother a tyre.