Not sure when Williams changed their Jet Assemblies. Here is one for 90s games. I don't know if it all works on your game.
http://www.pinballlife.com/index.php?p=product&id=1513
You probably will need to buy the parts separately. Body, skirt, base, lamp holder, metal ring, yokes, etc... It is not difficult to figure out the parts you need.

It was in 1976 that Williams went to the tall skinny pop bumper body which allowed you to replace the rod & ring easily without unsoldering anything. All you did was remove the bumper cap (unscrews), raise the playfield, then remove the two 5/16" nuts on the rod & ring. Then the rod & ring pulls straight up through the top of the playfield. The pdf page 3 of the Space Mission manual explains it:

http://mirror2.ipdb.org/files/2253/Williams_1976_Space_Mission_Instruction_Manual_Jan_1976_no_schematics.pdf

http://www.pinballlife.com/index.php?p=product&id=351

Other pop bumper parts are here:

http://www.pinballlife.com/index.php?p=catalog&parent=71&pg=1

The original pop bumper coil in Flash was SG-23-900-DC. Williams has changed their coil numbers a couple of times over the years. These guides will help:

http://www.pinballmedic.net/coil_chart.html

https://www.flippers.com/coil-resistance.html

The current number for your coil is AE-23-800-06.

This online parts catalog shows exploded views (and part numbers) for all of the assemblies in your machine:

http://www.planetarypinball.com/reference/partsmanuals/WMS_Parts_1980/index.html

https://pinside.com/pinball/forum/topic/vids-guide-to-rebuilding-pop-bumpers

I use this as my goto guide

Sorry to bump an old thread, however i'm having trouble sourcing coils in Australia for my Flash jet bumpers. The coil number is SG 23 900 DC as stated above by KenLayton , but the charts he references in the post say that the coil he says substitutes has a different resistance and different number of turns. The chart does not show a replacement for the 900 coil.

Does anyone know for sure what is the new part number for this coil so i can track it down? Marco has them under the old number but wants $50US to ship 1 coil to me.