Hi and welcome to JustAnswer,Thank you for the question and your patience. Should you still need assistance for information purposes only...Initially, bear with us; re-confirm and post back with the complete model number(s) of the monitors. How many monitors? ...all exhibit the same symptom(s)?
The only easy user doable attempt would be to check, re-seat the Video Output Board and all wiring/connectors if all monitors are experiencing the same issue. Strongly consider replacing this board P/N WJ-PB65M16 (with a service board if can be made available) as this would serve as both an attempt of a fix and as a test by process of elimination.
If comfortably able and feel safe to do so, are you then considering a DIY (do-it-yourself) repair approach?