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Parts for JEC8430 - AppliancePartsPros.com
Your model number seems to be missing the last 3 digits so you will have to choose the correct unit from the Matching Model Numbers section.

See the attachment for your tech sheet.

For some reason your fix did not work so now to get L1 (black) to the rear infinite switches/elements it must feed through the left front infinite switch.
May even be the L2 (red) but is more likely to be the black.

You will need a meter to track down the open using the wiring diagram and the wiring layout diagrams.

Be sure to remove power from the unit when doing this.