KX-T: KX-TA624 Strange things happening

[Bob Bruskin]

I received a call from a customer about an hour away.  He has a small business with four CO lines and eight 7700 series stations and two 7895 cordless sets.
I installed a KX-TA624 about seven years ago with one expansion card [6 x 16].  No problems since till now.
His complaint was Line 4 light was always lit and the line was dead when he tried to access it.  I had him reboot the KSU.
The first call that comes in goes to Line 4 [Lines 1,2,3 not busy]. After the call is completed, line 4 stays lit and all calls properly route to Line1 and if busy to 2, etc, the Line 4 light stays lit and that line is not usable.
I have not been on site yet, thought maybe some previsit ideas might help.
Thanks

Bob Bruskin
Halstead Electronics Ltd.

Cell:         914-403-1537