My wife was bequeathed a Howard Miller Grandfather Clock and there were several problems with the pendulum... first of all, the pendulum was replaced previously and the replacement was the incorrect pendulum. It could not be made long enough with the adjustment screw to keep proper time as the pendulum was too short. So, to correct this I made a pendulum lengthener to hang from the clock mechanism and then hang the pendulum from it.
Secondly, the clock had been moved several times an care was not taken with the pendulum and there are some plastic parts on the back of the pendulum that were broken, with some pieces missing. i had to re-engineer the parts to fit the pendulum in order to allow the adjustment rod to actually function. The part at the top of the pendulum was broken and the adjustment rod did not have an anchor point that would allow the pendulum to adjust. As a result, I created replacement parts to anchor the rods and space them appropriately.
If you look in the pictures you can see the parts mounted on the back of the pendulum in the reflection in the mirror in the back of the clock.
The author marked this model as their own original creation.