HP catridge Problem Pls help!!!

[dinesh_mettur]

hi dudes

am having Hp 3940 deskjet printer , just now i refilled my HP 21 Catridge black
but now its not working fine ....

When i take a copy of print out the printing Quality is bad ,

pls help me !!!

 

[shantanu]

if not then do so with a soft cloth..