Yeah, garage guages are usally always broke or at best poorly calibrated.
The old propeling pencil type guages are good if you want something simple that doesn't need batteries.
Eitherway, a wee digital keyring or pencil type from Halfords is better.
As for the valve coupler on servicce courts pumps, I've never had an issue, usually I just have to move the wheel slightly and manipulate the hose (
oo err)
Cheers
On a completely irrelevant note of disbelief, some chav has just popped my off-side side light and had off with the light fixture.
There's a nice shiney clean cut where the terminals connected to the light. What a gypo!