Both flippers and the magnet are weak even after a flipper rebuild, a new magnet and serviced boards.

Flippers and magnet weak after rebuilds: replace the Fliptronics board

Cause: The Fliptronics board, which drives both the flippers and the magnet on this game, was at fault.

Checks

• When the flippers and the magnet are weak together, suspect the Fliptronics board they share.
• Check and redo the Fliptronics board connectors before replacing the board.

Fix

• Replace (or have repaired) the Fliptronics board.

Systems

• WPC-Security (WPC-S)

Games

• The Shadow

Related tips

• How Fliptronics flippers work
• Fliptronics: flipper button does not register in switch test
• Fliptronics board versions
• Checking flipper buttons and EOS switches in switch test
• Flipper stuck up but drops when the power goes off
• All flippers kick once at game start and then go dead
• Fliptronics and WPC-95: weak flipper
• Games that came with Type 2 flipper opto boards

Source: Pinball Repair help group!! (Facebook group)