unblock slime presta valve My Son's bike has slime inner tubes.  The bike has been sitting in the garage since last summer and the front tyres valve now seems blocked.  Its has what feels like 15-20 psi in it but I can not get the valve to let any air out or take any more in.

I have no idea at this point how to get it to unblock the valve so I can use it again.  For that matter I don't know how I could get the tire off as it has a reasonable (not ridable) amount of air in it without slashing the tyres (nice kings 2.2 which are pretty new).

I have tried putting the pump on it and putting a bit of air into it to try and clear the blockage but that didn't do anything.

Any ideas please?
Use a valve core tool to remove the core of the valve, and then clean it using a light solvent.

   

It should be only a few minutes work. If there is a lump in the flat tire, the slime may have hardened, and the tube may need to be replaced, either way.

Hope that helps.