i had same problem like a year ago, i tried gluing them in but, the tacho needle would get stuck on like 3 grand, then i got to 5 and a half it got stuck again. it gave me the shits cause no matter what i tried it always happened, so i just took them out and still got them a year later. oh well. and i dont think you should have to take needles off, they do slide over with a bit of force..
but filing the needle might work, might give that a try