He rubbed a liberal supply on the chain of each wheel, and also on the sprockets.
The chain had come off the two sprockets and was lying to one side.
The projections or sprockets, Fig. 3, must be accurately set at a distance of 3/8 in.
The sprockets should be cleaned every day with a suitable brush.
He opened the film gate gingerly and removed the film from the sprockets.
He replaced the film on the sprockets and closed the gate with great care.
After the negative has been led over the sprockets you notice that it is allowed to make a loop of a couple of inches of slack.
The sprockets 180 working in the perforations pulled out the film and made the loop larger.
The worker rollers are fitted with sprockets and turned by a hand-forged chain.
The difficulty apparently was the result of the sprockets being cast and not machined.