Stop in for a cup of coffee

Plumbing solder works well also. Keep the 40/60 hard to find now.
Almost $35 per pound! McMaster has it in stock.
My plan is to solder it place. Drain the coolant to just above the top of tubes. Use some emery cloth to make sure the bracket is clean. Then try to hook one of the holes in the bracket with a spring or bungee.