i cant find my printer on my network

ive got an internet cafe with 5 pcs. my main pc behind the counter has the printer connected to it. the prob i have is that 2 pcs can use the printer via the network but to cant.
yes ive done the add printer thing. when i go to add printer it says is printer connected to a network so i go to browse but it cant find it. so i typed in the printer name to find it that way. the pc says cannot find printer it may not be connected

 

Are the two in question in the same workgroup? Also, is the Firewall set up to allow the sharing of the printer?

 

3 of them were working then 1 of them stop working for no reason. there