Huntman,
I use hot melt on all of my broadheads. After I get them to spin true, I shoot/practice with them for at least a couple of weeks before season opens into a foam block target and the glue never gets loose.
I practice with them and then I hunt with them.
(I check and double check that they are still tight before I hunt with them of course)
Mo. Huntin is right, clean and de-grease everything!
I use a propane torch to burn out any machining oil from the broadhead. Be careful and heat slowly so you don't overheat the broadhead so you don't "lose the temper" of the broadhead.
Clean with acetone or Denatured alcohol and glue 'em on. Spin test and reheat and spin again if they aren't straight.
All the luck!
John