Weights could also be added to the top of the pendulum bob to speed up the clock's rate.
An ordinary, rear bicycle axle could no doubt provide the donor material and save the purchase of a special die to cut the thread on a bare rod.
A cycle wheel fixing nut would do at a pinch in the absence of an original.
The cast rating nut has the appearance of a water valve wheel. Here the underside is shown.
Invar is a nickel-steel alloy which has almost zero thermal expansion. Changes in temperature should not alter the rate of the clock.
A threaded crossbar [with large washers to trap the suspension spring] normally rests in the cast-in v-grooves in the Pulsynetic master clock movement.
The entire C6/C7 bob. Removing the small screws in the top plate will allow the inner weights to be fitted and removed for examination.