I recently picked up one of these from a yard-sale that appeared to be in excellent condition but is missing the cylindrical piston that pushes the lube down the lube chamber . It is difficult to get a measurement on the thread size as it is below the lip of the tube . I can make up one on the metal lath but cutting a small internal thread is challenging so if someone happens to know what the thread and pitch size is then I could probably order a tapping tool and make up a new one . Thanks a bunch if you can answer this inquiry .