I am trying to adjust a Congreve Rolling Ball Clock (reproduction) for a friend. I have it running well but cannot slow it down enough. I assume the principal timing adjustment is by adjusting the radius of the crank that lifts and lowers the table. I have that reduced as much as I can and it still gains a minute or two per hour. Is there some coarser adjustment that I am not seeing? [The lever at the bottom of the lift rod appears to be more for putting the table "in beat" -- am I correct?]

Thanks for any help or advice (other than "stay away from these clocks" )

Try another ball.
I got mad years ago on a congreve clock, till i found out, that the ball was not correct.
In a shop that sells bearings, i picked out some other balls with minimum different diameters and one of them was perfect.
Be aware, that the ball speeds up, in the first hour. And a minimum changed results a maximum effect.
If you need the guidance for a "Devon clocks" congreve clock, i could send you my copy by FAX if you want.
Best regards
Holger
Hope my english is OK.

Holger - thank you for the suggestions. I will see if I can find a very slightly smaller ball. The clock I have looks identical to the Devon Clocks reproduction, but the ball takes 30 seconds to travel one way, rather than the 15 seconds described on their WEB PAGE. Although the seconds dial is marked every 15 seconds, the hand moves in 30 second increments. I will also write to Devon Clocks and see if they have any suggestions.