My first post as a new member to this thread. Found this forum googling for answers on this subject and decided to ask after noticing some quite engaging and very informative topics here.

Well to start off, I got rid of my 8 year old Agfa Arcus II, a midrange flatbed primarily used for restoration work, after it started exhibiting vertical line noise in the mids to shadow regions of my scans. Bought a refurbed Epson 4870 and wanted to know if there was a definitive image/scan test that could determine any hardware defects or quality issues to look for since it is used. I've done the usual Photoshop Equalize test on a sample image scan to check for artifacts, none detected. Thought maybe some here know of something more indepth.

It's my second scanner and can only compare it to my Arcus which claimed a 68 billion color sensitivety. Don't know if the Epson has this, though it seems to exhibit more noise than the Arcus in the form of tiny hot red clustered 2-3 pixel size noise peppered throughout. The Equalize test on a scan of a blank sheet of white paper for checking scan area sweet spot shows quite a bit of noise over the Arcus. Don't know if this is a defect.

Any suggestions would be appreciated.