I found that when the Playbook does not accept charge, I simply disconnect the charger, and then put it back again.
The control for the Playbook's internal power and charge regulation is controlled by a uPC controller in the power circuits, which is instructed from the main CPU. Sometimes it does not respond properly. When disconnecting the charger and re-connecting, it does a re-set of this area. The more drastic approach, but rarely required is to do a re-set of the Playbook. 
With the optional quick charger, I like the magnetic connector. I have had instances where there is poor contact. This connector uses surface point contact rather than insertion. As for preventing wear and tear this is an excellent system. The fix with the point contact connector is to take a tissue and carefully clean the contacts on both the Playbook connector and the charger connector. Be gentle with this. The tisssue can be slightly dampened with a little alcohol, or better contact cleaner for electronic devices. Do not ever use water based cleaners.
The problem is sometimes a small amount of dust or dirt can get on to the connector contact surface. With surface contact type connectors this is a common problem. With the insertion type contacts, the connector is normally kept clean by the friction of making the connection. With these the dirt or oxidation problem has to be severe, or a connector has to be defective to have a contact problem.
Jerry G. 
