Measuring voltage on through the hole soldered components on PCB

[cepwin]

I'm trying to debug why I'm getting a white screen on the DSO-138.   Test mode indicates an open and I'm trying to measure the voltages on the various points they specify.   When I go to measure the voltages around resistors, etc. I get unstable values on my multimeter (and in some cases wildly off the specified values.)   Any tips on using the multimeter to take these measurements?    Any tips on finding opens?