Pool Heater: Raypak 2100 reassembly

Looking for some tips/tricks on reassembling the burners on a Raypak 2100. There are 13 of them!

The gas supply orifices were clogged with debris and spider webs. So I had to disassemble them from the burners and clean them out.

The burners connect to the back of the assembly through slots in the back, but they still have lots of play and are easy to fall out. Trying to line up 13 (flopping) burners to the 13 orifices has proven quite a challenge (which I have not achieved).

The whole assembly is at the bottom of the heater with access from the front (orifice side).

I did not (nor know how to) pull out the entire burner assembly. I rotated the orifices arm 90 degrees (or more) to get access to them.

Any tips or tricks would be greatly appreciated.

TIA!
Lenny B.