The tedium involved with details when or if using Ukelele, may be worth the trouble. Just so long as the process is not difficult to undo if undesired or odd results occur.
Hopefully there is an answer for older Macs with no upward mobility.
One is a repair on older Macs, such as wegenermedia & others do.
Of course, with an intel-based Mac, there is Snow Leopard. A long
way to cure a keyboard issue. Easier to pack it up for a visit to some
repair facility, after working out shipping details to their specificiation.
Except for the costs and loss of use while it's away on sick leave.
http://scripts.sil.org/ukelele
It may be OK or a reason to add wild stuff to your coffee.
Good luck & happy computing! 🙂