1971 Ford 2000, 3 Cyl, Gas - Has original instrument cluster, tach (proofmeter) was not working. Installed new cable from generator. It has begun registering, but inside the cluster, a gasket/seal has slipped or pulled in from around the edge of the cluster, and is interfering with the tach indicator needle, won't register over 1000 RPM. Is there a way to access the inside of the cluster? I was afraid I would break it because it did not come apart easily. I see screws on the back, but none that obviously lead to the display area of the unit. Thanks for any advice.