I am attempting to complete one of these models, but I am having a lot of trouble to get the lubricator to work. There does not appear to be enough travel when driven from the valve rod as per the drawings/ articles in Model engineer. I have tried the ratchet type as well as one driven by an eccentric cam, but to no avail. the one in the article by Martin Evans looks very complicated to make, and as yet I have not found anywhere that I may be able to purchase one. Anyone out there who may be able to help?