Antique and Vintage Clocks

If you are following this blog this is the same clock as the previous post. Since the movement was very dirty, I cleaned it up (ultrasonic cleaner) when all apart and reassembled and oiled it. It is a one-train movement, so not many gear wheels and pretty easy to work on. You can see by the size of the clock, a photo of which is in the last post, that the movement is quite small.

I thought with a cleanup and oiling it would be simple to get it going again but no such luck. I know that there is power getting to the escape wheel because when I disconnect the anchor it spins like a buzz saw. When I reconnect the anchor it runs for about 15 seconds and stops. I would like some ideas to get this clock running but in the meantime I have attached some photos. My question, it there anything missing here? This clock doesn’t have a suspension spring or a crutch which I find unusual. And what is that screw thing for? Comments and suggestions would be appreciated.