×I can understand the general idea, using the brains to stop the gel babies from continuing to follow you, but once I get two in place I struggle to be able to get any more in place before one of the two move about.

I ponder if part of the solution involves moving the brains a bit.

×Observe what changes if you put a brain vertically or horizontally next to a pressure plate.

×Two brains for both left side, then getting the other two in place and grabbing a brain from one of those left ones to keep everyone happy. Could probably work mirrored, too.