The gear puller is the worse puller I've seen..made out of junk. The threads in the gear itself are much stronger as the it's tempered. I first take a 3 corner file and clean up the threads, and it may not be too late for you to do the same. If it is, you can use a miniature wonder bar or something similar to pry the gear up from beneath (after removing the screw), and driving the shaft out. Removing the seal, pry out with something like a screwdriver. Installing, I'd coat the seal with WD-40 (it's not a oil but a moisture barrier), place on shaft and use a socket that is slightly smaller then the seal and install with a hammer. I use a leather mallet, but a hammer will work.
If you should need a puller contact me. I can loan them out, like loan a tool from Auto Zone/Advance