I have one that I thought the display was getting dimmer on.....It is certainly a lot dimmer than my other Jet 005 display but was not certain if it has gotten dimmer, or was just dimmer than the second one I set up a few weeks later.
I can still read it if positioned directly in front of it.......but move away a bit, or from an angle it is near impossible - Whilst my other one is much easier to read.
If you have noticed it then perhaps mine has gotten dimmer with a bit of age? The unit that is dimming has probably been in operation for approx 3 months.