I just got a Touch-N-Flow (TNF) yesterday and put it to use tonight.  For the most part, I really like it.  The needle makes a precise application of the plastic solvent and allows me to make fantastic seams.  But, I also end up spilling solvent from the squeeze bottle when filling the glass tube, and/or having solvent run down the outside of the tube.

I feel like I'm missing some trick toward using this.  Any help?