That's sad @Calvans_Kliens , one would imagine that the support would be able to reset the loadouts.
I found this thread where someone had this similar issue with a pilot class and they had a funky way to fix this : https://forums.battlefield.com/en-us/discussion/101845/the-repair-tool-for-my-pilot-class-is-gone-and-i-cant-get-it-back-bug
Basically what they did was that they joined an empty server first, and spawned in as a pilot/tanker, and then quit the server. Then they went to another server, and clicked on an empty cavalry ticket, without spawning one. Now, apparently for them at least, the weapons visible at the bottom were the pilot/tanker's rather than the cavalry's and they were able to arm the Wrench back to themselves the way you'd equip gadgets to any other class.
I am sorry for the issue you're having, and I hope that workaround would perhaps be helpful.