Looks like the wrong stack. Your fathom has separate high and low voltage switches and the new one is single high voltage stack.

Definately a wroung switch stack.

tried looking and can't believe how difficult it is to find the correct stack.

ASW-A20-23 flipper switch with heavy duty contacts
ASW-A10-45 flipper switch with light duty contacts

it is made up two switches, one for the high current with tungsten tipped contacts, this works your lower playfield flipper and the other with light duty contacts for your lane change, both normally open.
wouldn't matter if the lane change switch did have tungsten tipped contacts.

https://www.pinballlife.com/search.html?Search=asw-a20-23

but in the picture the -23 appears to be closed, you would need to alter this.

in the past i have used the original insulating sleeves and made the flipper stacks up there, using new parts but adding/changing the bakelite spacers to accommodate.

no surprise parts aren't made to original specs.

yep its the wrong stack.
suggest you buy the secondary switches from the same place you get the flipper kits ( either pbl ones are pbr ones).. mixing the round and square blade styles doesnt work well

Looks right from here.
Did you ask Steve? He’ll know for sure.

Secondary switch is for the lane change and is not designed for high current. It should have a 3rd lug for the diode and be fully insulated from the high current contacts used for the flippers.

Call Steve at PBR. He'll tell you. Get the high current switches