1982 Spectre 1100 Tach issue.

Use an "engine cleaner", not carb cleaner, don't want to break down the varnish coating on the windings. Just spray some around the working area of gauge. This will dissolve the tack, blow it out, recheck function. Engine cleaner won't damage anything and what i use is water soluble. 

Cover the display, heat up the needle center and pop it up using two tea spuns as leveler, what else do you need.....

If the needle and hub is plastic I wouldn't use heat.