New handle? As in, oversize bolt knob, or install and entire bolt handle on the bolt body? Or sticking some more onto a cut off bolt handle?
Some clarity will be required, in order that you get the details back that you need.
I'll second the pictures request, as it does make clear the required work.
<edit>Just re-read the OP. Handle came off? How was it secured originally? If it was soldered, it can be a right PITA to remove all the solder, and the stuff can play hob with trying to weld parts together, due to the contamination of the solder that is there. Following the original practice but doing a good job of it (which sometimes gets missed in a production environment, hey, stuff happens!) in the event of a failure, is usually a good plan.
Nothing wrong with silver solder, if done well. Clearances have to be kept fairly tight, and the part has to be properly cleaned and fluxed.
Cheers
Trev