As others have suggested make a new armboard a local machine shop should be able to help you. Tri’s setup jig is a little “rough” when I mount Triplanar arms I use my DR Feikert jig on the tonearm directly then mark the hole locations on the blank armboard.
Are you selling the 4.5 ? If the price is right I’m interested
Best of luck
Peter
Are you selling the 4.5 ? If the price is right I’m interested
Best of luck
Peter