One of many great things about your find Robert, is now I know what those activators looked like brand spanking new. I always assumed an embossed "GE" emblem on the top of the cap just wore off; now I know there wasn't one!
The smaller flume is for overflow protection. The earlier solid-tub models had a dedicated suds return flume; starting with the 1961 V-12's the suds water returned from the bottom via the pump, the way it went out.
I was always thought the inlet flume on the perf-tub Filter-Flo's was defective. Especially when compared to the solid-tub flumes inlet water from the V-12's spewed and barfed into the washbaskets. It did the job when spray rinsing but it was messy, like watching a woman take a leak. After learning what I've learned on this site, like suds-lock, I imagine it was designed to go all over the place so some would end up in the outer tub when spray rinsing. Again, on the solid tub models, there was a neat little slot underneath the main inlet flume that directed water precisely into the outer tub to wash out suds.