Best way to locate a 4k stray resistance between 2 bus lines in a PCB?
The way I do it is remove the pins attached to the bus one by one (or all at once) until the offending part is found (and in your case the resistance would go back up to 44k). This can be done by unsoldering a pin and then lifting it up carefully. SMT parts will have to be lifted completely. Try to rule out the easiest parts first.  

Another way I have done this in the past to find power problems (a short is similar to yours)  is to cut a trace (which may not work so well for high speed signals( 10Mhz+), but works great for power an low speed signals. I usually cut the trace to cut the traces attached to the net in half, and then test the two halves. Once the offending part is found it can be replaced.

A hi res IR camera might be sensitive enough to detect a temperature change of the offending part if you have a board to compare this to.