Get a needle nose plyer and unscrew the stems and just carefully dig/pull the old gaskets out and put the new ones in and re-installed the stems.

 

Sealrights come apart by removing the C clip on the back.

 

Do not just replace the gasket; replace everything. you should buy the kit.

 

if its not keeping the charge in the hose, use the re-build kit, very easy to install

if its leaking a little at either end, or simply not holding a vacuum, dont wast your money on the kit, both the O-ring and Gasket (depending on which end) are replaceable on their own, O-ring done with a pick, and Gasket done with a needle nose and a pick