I have just reolaced 2 radiators using knowledge gleaned from this site. However I have a slight problem. I removed the old tails using an Allen key and spanner and replaced them in the new radiators. I carefully wound 5 layers of PTFE tape around before screwing back into place. Unfortunately on filling the system I discoved a slight leak from each tail inserted with the allen key for the lockshield. i drained down,removed the lockshield valve and put more pressure onto the allen key to tighten the tail, unfortunately upon refilling the system i have not solved the problem. What would you suggest? Do I repeat the procedure applying even more pressure or could I over tighten? Should I remove the tail and re apply PTFE with more layers? Is there a compound that I could use, that may be more reliable than PTFE? Hope that some one can advise me on how to complete this project successfully?