I just found a "UniCom 1216" calculator for $1.50 . It's a bit larger than an HP-97, no printer, and basic four-banger business adding machine functionality. (Everything seems to work fine.)
The display is an orange fluorescent (I think) 12-digit unit. I notice that the higher-order digits all look nice and crisp, with each segment clearly dilineated with razor-sharp borders.
As I look toward the digits to the right, they get progressively less well-formed. Most the lower five digits' segments each have a "blob" of orange hanging off of one side or end -- it's as if something has "bled" out of its original confinement.
The problem seems to be worse on the most-used segments (keyed digits enter from the right). Also, some of the segments on the rightmost two digits are dimmed.
Is this a common problem with fluorescent displays, and is it, in fact, related to frequency and/or total duration of use?
I don't expect anything can be done about it -- I'm just curious.