Repl2x: second extruder picking up raft

Hey all.

I have a Replicator 2x and I'm trying to print using a raft. What I'm seeing is that as the first layer of the raft is being laid down, the second extruder usually catches a high spot and rips up the raft from the print bed, ruining the print.

What do I need to do to avoid that?

Bed: 110° with kapton tape
Extruding ABS @ 230° on right extruder
Left extruder left off

I recently calibrated the bed using a business card for height.

Thanks.

1. check bed level first.
Then do step 2.
2. make sure the nozzles are the same height or no more than .002" difference.
Here is a link to the instructions.
http://support.makerbot.com/troubleshooting/makerbot-replicator-2x/mechanical/my-extruder-nozzles-are-at-different-heights_11422