I just removed the old fork from my winter project road bike and put the new fork in. The new fork is the same size and has the same threading as the old one.

When I started to thread the Upper Stack onto the new fork it easily goes on for about 25 turns and then just stops. I put on a pair of leather gloves and turned as hard as my hands could take but it didn't budge. I thought something might be wrong with the threading on the fork so I took the upper stack off and screwed on the spacer which went all the way on. I also took the Upper Stack and screwed it back onto the old fork which went right on.

Is there a tool that I could use to help turn the upper stack? It is perfectly round and doesn't have any notches to use a C Spanner. I tried to use a clamp pliers but just ended up scratching the stack.

Any suggestions?