A hypodermic needle is a useful tool for getting glue or resin (not too thick) into a split or opening joint, as you can get whatever you’re using right where it can do most good and fill the cavity up from the bottom. Try chatting up your local friendly District Nurse who may be able to let you have a second-hand disposable syringe and needle - If you can convince her of your innocent intentions! Warning. Some of these synthetic resins contain poisonous substances which can be washed on skin, but which can be a bit disconcerting circulating in the bloodstream. You will also appreciate that it is not a bad idea to keep your needle out of the reach of Little Willie.
Editor's note - This article is from Reflections No. 11 Autumn 1973, page 4 and has been captured by OCR, so typos & errors are possible. In 2018, a syringe and 'tube' needle, as used for refilling inkjet cartrides, are easily available.