Hi Jeremy
We have the Fowler small size caps that fit not only the Syphon Wick Lubricators but also the eccentric oil caps I believe as well.
Either way if you confirm the tread of the caps we can supply the caps and the cones and the special conical springs. If for any reason the spring needs to be longer we can have these made to suit the length you require.
Give me a call if I can help any more. Stuart 07785 258169
Take a look at our cataloge on-line here, page 129.
http://www.heritagesteamsupplies.co....cat.html#/128/
Cheers
Stuart