Most (many?) of us here don't use macros, but if you think you can create an AfterUpdate event for your control (from the property sheet Event tab) then this should work.
Code:
Private Sub YourTextboxName_AfterUpdate()
If Me.YourTextboxName > 2900 And Me.YourTextboxName < 3200 Then Msgbox "Lift is due for 3,000 Hour Service"
End Sub
Don't duplicate the first and last line, and provide the proper control references. The above is untested and assumes the values being checked are numbers and not text. It seems like a one-off solution though. I wouldn't write it that way for say, 10 different service messages.
Last edited by Micron; 05-18-2017 at 03:15 PM.
Reason: code correction
The more we hear silence, the more we begin to think about our value in this universe.
Paraphrase of Professor Brian Cox.