Try the wacky reels in the Cleo and report back. If no change, swap Cleos reels in and see how they act, at least you can eliminate the reels and/or bulbs.
And BTW, we use 161s in reels frequently as well, with no ill effects. Yah, yah, they don't light quite the same, but they do work. Sometimes, you can't do everything exactly by the book...
For some reason, it seems like we had an SB/SG combo on a 5 reel machine that wouldn't light properly, but I can't swear to it. I might still be haunted by the display issue that it caused!