As stated on the Grubby page, there are 3 pieces of metal coming from the
bottom of the Grubby receptacle at different heights to correspond to the
sections on the plug.  With repeated use, these pieces of metal get bent making
it very difficult to get the plug in and out.  Once the metal pieces are damaged
and bent, attempts to plug the cord in do additional damage to the connection.
The receptacle in Teddy and Grubby is identical but for some reason, Grubby
seems to be more prone to damage.  His connection is also more time
consuming to change and repair as it is not as accessible as Teddy's easy to
reach connection.  My personal recommendation is to put the connection cord
and Grubby is the leaking of battery acid from the batteries.  Both Teddy and Grubby have the input for their cord right next to the
battery box, and any leaking of battery acid with corrode the connection.  I have seen several Grubbys in for repair where the plug
is literally solidified to the metal pieces in the connection as well as the plug.  Attempts to separate them actually break pieces of
the plug off.  As far as I know there is no replacement plug other than those taken from other cords where the plugs are OK and
into Grubby and leave it connected to Grubby, just unplug the cord from Teddy .  Another major cause of a stuck cord in Teddy
the cord wires are damaged.
First off, check if your batteries are good and inserted in Grubby in the right
sequence.  Make sure there is no corrosion on Grubbys battery springs or
cover.  Make sure you have a WORKING Teddy Ruxpin, a tape that contains
Grubby in the story, and a World of Wonder connection cord inserted into both
Teddy and Grubby.  If possible, try another tape.  You can have a tape that
works Teddy perfectly but the channels containing Grubbys data are
damaged.  Not every story has Grubby data although most of the time if you
play a Teddy only tape (example...Lullabies), there is data that opens and
closes Grubbys eyes on occasion so he "looks" alive even though he does
not do much.
These are the metal contacts that bend when the cord is
roughly plugged in.

If these sections are not exactly lined up with the sections on
the plug, Grubby will not animated properly