727 doesn't shift into second gear like it should

To make a long story short, I had a transgo kit I had bought some time ago to install in another trans. I drilled a hole too big in the separator plate and put it all away. I had forgotten about having it until I was sent some paperwork by email so I went to the garage and there was the rest of the kit. I put the spacer and the large spring on the rear servo and readjusted the band. I also made the spacer for the accumulator. My question is that in the instructions it says to install the small plug with the hole in it in the front clutch apply hole on the trans where the valvebody goes. Should I use this also? And what does it do? Is the plug for the band overlap remedy or for other reasons.

Just for a reminder I am still using the B&M kit in the valvebody.