You changed the printer.cs and nothing has changed?
You performed the following steps?
a. Make sure that you are compiling the project without errors. "Build" in Visual Studio.
b. Copy your Peripherals.dll ([...] \ Retail SDK [CU] \ POS Plug-ins \ POS \ bin \ Debug) to the extensions folder (C: \ Program Files (x86) \ Microsoft Dynamics AX \ 60 \ Retail POS \ Services \ Extensions)
I Hope This Helps!
Regards,
Rodolfo Recalde.