Malcolm
Could not help noticing that the bottom "pull" pallet is slipping off the escapement wheel teeth. This is one of the disadvantages of the Grasshopper, but it can be corrected. One of the major causes is lack of drive force. When this is the case,the escapement wheel moves slower than the swing of the pendulum, reducing the pallet grip and causing it to just slip off the tooth.Usually an increase in drive force will solve the problem. Secondly the tooth should connect in the pallet corner. And thirdly the pallet should be so counter balanced that the pallet falls onto the stop with as little force as possible. If despite your best efforts the pallet still slips, you can file a small hook in the pallet corner, which will give the pallet more grip.
The grasshopper is because of it?s nature more complicated than a deadbeat, but worth the effort when it starts running smoothly. It is mostly just a case of getting your head round the concept of the Grasshopper.
Dave