Finding and Fixing Intermittent Friction in Gear 6 CC16
I think i discovered the underlying cause of inconistency in Compact Clock #16: It is the long plastic snout that drives the hour hand. Gear #6. It pushes through the front frame. I'm thinking it has a lot of friction simply rotating through the frame, plastic on plastic. Then I must push the hour hand and the minute hand onto that plastic shout. The "push" required to mount the hands translated into displacing the arbor inside the frame. Or, I pushed the hands on, the pulled the "back" a bit, and that left compression inside. The gears which spun easily then were compressed and thus stoped turning smoothly. The clock seemed to run at 1/2 speed even though the pendulum ticked at the normal rate. This may have been the surprise -- the friction clutch is slipping because there really is too much friction. It's not the clutch. It's the compression of Gear 6 against the backside of the front frame.
You who are engineers may have better ideas, but that seems to be the source of friction that causes inconsistency in Compact Clock 16. (Inconsistent: When it runs it will continue for a long time keeping near perfect time. If I mess with it to change hands or add a "Tempus Fugit" bob, then It loses time, maybe one hour lost each four hours even though the pendulum is normal speed. There is always an antecedent event.)

Those are all good points. This clock is unique in that many gears share a small number of arbors. This required several spacers or other methods to prevent one gear from pushing against another gear.
Pushing the hour hand onto gear 6 can certainly have the side effect of disturbing the position of some of the spacers. Maybe I should change the assembly guide to add gear 6 and the hour hand to the front dial as one of the pre-assembly steps. Then the hour hand would already be installed when gear 6 and the dial get added.
I usually leave gear 6 and the hour hand in place when I take my clocks apart. Making this the default assembly process might eliminate one risk factor.
Glad to hear you have your clock working properly. Once everything is tuned up, SP16 is one of the more reliable clocks.