Hi David,
I'm repairing a similar clock, which I bought at auction.
On that on that type of clock they used an anchor (held by a riveted brass bracket)which is situated below the escapement wheel, compared to most other clocks, where the anchor sits on top of the escapement wheel.
The movement (and force) of the anchor pushes the
escapement wheel upwards and enlarges the pivot hole.....therefore the force that's supposed to move the anchor/lever/pendulum is lost.
Repair: Remove rivets,remove (escapement wheel) bracket....rebushing pivot hole to correct size.
Use suitable screws to hold bracket in position
(Of course this may not be the only problem!)