Charges only when I strongly tap the laptop

Hello. I have an early 2011 version. The mac works fine but charges intermittently. I have changed the battery. I have cleaned the contacts and tried another charger. When the magsafe is connected and not charging it still keeps the mac powered and the powered symbol appears in the UI but says not charging. I've done the SMC and PRAM.

What can I do as I don't want to continue to bash the laptop to charge it?

Thanks