The Natural Philosopher wrote:
Aenuff wrote:

snip
Is there a trick I can use?

Yes. get tow decent hose to tap connectors, and a length of hose.

Connect one end to youir kitchen tap which should be on mains pressure

Connect the oher to teh problem tap, and open both.

The mains pressure will blow the air back to the tank. If you overdo it
you will blow water there as well, and flood it, be careful

Anoher trick is to suck at teh tap that doesn't work.

A wet-dry vacuum cleaner can be useful, if you don't want to swallow
lots of water.