Some manufacturers require dealers to have a trained technician on staff. That means that the dealer pays to send the person to the manufacturer to become trained. I have been trained by Roland to work on the Eco-Sol printers. With that training I have also worked on Epson, Mimaki, Mutoh, and Brother. Once you have an understanding on how to work on an wide format inkjet printer you should be able to work on most. Keep in mind that it may not be so easy to obtain parts for all printers. You will also need access to service manuals and software. Epson does not provide downloads of the service software (used to reset counters and perform tests) but requires you to send in your computer so they can upload and unlock the software. You will also need the unlock codes for machines to launch their service modes. The repair service offered by dealers and manufactures is a very profitable business and they do not want competitors taking that revenue. Service on printers will cost the end user between $70-$125 per hour plus travel costs if not under warranty.