Hi Frank,
Not having the clutch lever is a big disadvantage as it is possible that you may not be able to get sufficient tension on the linkage to make it work.
The way it works is that when the lever on the handle bar is pulled in it pulls the clutch linkage rod upward (i.e towards the user) and the yoke moves towards the left in the direction of the spring. As the lever is pulled all the way in the yoke engages the left side of the collar and pulls the clutch inner to the left, compressing the spring and withdrawing the clutch inner sufficiently out of the outer to disengage the drive.
The spring acts between the clutch inner and the bearing housing on the mower frame. This results in the clutch being in the engaged position when the spring is not compressed. When in the engaged position, the yoke sits free in the collar groove at the back of the clutch inner.
The lack of lever will make it difficult to get the clutch to disengage as the spring provides good resistance. The spring is well set into the clutch inner and there are limited leverage points in that area making external compression of the spring difficult. You may find that if you try to pull the linkage rod back in the direction of where the clutch lever would have connected to the handle bar you might get it to pull the clutch inner out enough to get it to disengage momentarily. I would exercise caution doing this though as it will need some strength to over come the spring tension. The best option would be to make up a temporary clutch handle.
The engine is a Villiers Midget. Many parts are available still in the UK. As parts like HT contacts were common across Villiers engines, Vintage Air Cooled Engine Spares may have what you need.
Kind regards
Sir Chook
