I have made a tool to help get the glue into the tip top. It is a large sewing needle with the eye end pushed into a cork. I then heat the hot melt glue and get a layer on the needle. While it is still warm or reheated I use the needle to work some glue into the tip top. You can also shave thin slices off the stick of glue and push a sliver into the tip and heat it in the tip. I put some from a hot stick on the rod tip and put them together. Sometimes if the trapped air can't get out of the tip top it will try to push off, rotating it into position slowly usually works.
Hope that this helps.
Dick xfishcop