Problem was solved. We went over the proxy sensors again, and found the rear zero degree proxy was staying on, even though it was not making contact. Replaced that proxy and the rear wheel will now change into forward/reverse mode.

Hi Nic,

Sounds like you have some good checks already completed. Need to step through the process, Might be a damaged cable to a poroxy, might be a valve or directional lever. Depending on truck config/age there might be lasers.

As you are in Canada, you can contact the Combilift North America based Technical Team. They are based in Greenboro NC. If you go to www.combilift.com, scroll to the very bottom, you can submit a "Technical Support" request. The form asks for truck SN, contact tel no, etc to help identify the problem and to contact you back. The tech team will then contact you. Here is a direct link here https://warranty.combilift.net/technical-support-form/
There is no limit on the questions, truck age etc, and no charge for the support

Hope this helps,
Richard