530t modified and still a problem

I have a customer with an E350 van that I installed an R/S an 530T in about 5 years ago. All has worked fine 'till recently. windows roll down fine but stop (you have to bump the switch repeatedly) when rolling up. Swapped the mod but still no go. Got the dei tech tip modification sheet, popped off the two resistors they show but still no go. Checked power and ground (ground is at fact. location, 12V is at batt feed for ign switch.Checked voltage at mod and only drops to 12.5 min under load!!

Any Ideas?

Thanks

Check the pins on the power input harness to the 530T.  I had the same problem when I put one on on a friend's GMC Sierra.  Eventually the windows just stopped altogether.  When I tore it apart to diagnose, the power input pin on the harness was loose and was dropping voltage when it was trying to roll the windows up.  The pin and the harness showed signs of arcing.  

It had similar symptoms to what you're describing, the harness going into the module held a constant voltage, but the drop was in the connection to the module.  I had another 530t, I put that one in and soldered the new harness and have not had any more problems

Thanx

I'll try that