Section 10.2.5.4 of the manual has detailed instructions and a diagram to aid in assembling the Rockwell blocks.
http://www.usfirst.org/uploadedFiles...Parts-RevB.pdf
Make sure all wires being inserted into the block are stripped to 5/8" to ensure you are getting only copper and not insulation in the screw terminals. If you clamp down on the insulation it's going to wiggle loose, probably at the worst possible time.
Maximum Wire Size and Max Quantity Allowed per 1492-J16xx Terminal
1 - #6 or
1 - #8 or
2 - #10 or
3 - #12 or
4 - #14 or
4 - #16
Another thread that has discussed this topic recently is:
http://www.chiefdelphi.com/forums/sh...ad.php?t=61981
There are pictures of a correctly assembled PDB included.