Interesting post, what SEEPs are we talking about? Gaugemaster PM1?
It is first best to check the rods to make sure they are not bent or twisting in the hole, this could mean the SEEPs work but due to the extra movement in the rods they won't throw the point.
In terms of the SEEPs I am able to get them to throw with 14v at 800ma, if connecting directly to the SEEP to test, you need to make sure the power supply has enough amperage too, a Seep can draw up to 1 amps. If using a CDU it needs to have relatively high capacity capacitors 35v i.e. http://www.gaugemaster.com/item_details.asp?code=DCDCP-CDU2.
I use Digitrax Systems, so probably not the best comparison but mine are able to operate from a 1-2 meter distance using 16A rated cable.
Hope that helps.