The DRO on my PM1228 came factory installed BUT per the instruction manual the socket head cap screws used as a carriage lock were not replaced with hex head screws and so there was no way to tighten them down. To fix this issue the DRO scale had to be removed and I decided if I was going to have to take the time to realign the scale anyway I might as well redesign the mounting system to allow me to retain the socket head cap screws so I could use an Allen wrench in them.