Yes, you need a gear puller to break loose the injector pump gear. IMPORTANT! Before reinstalling your new VP44 pump, make sure the 'moon shaped' key is securely in the new pump shaft.
Notch the moon side of the key and hammer it in, or use lock- tight, or something! You need to make sure it's on top of the shaft secure. You may need several tries. You will have to use a mirror to align it with the gear in the gear case.
But if you drop it in the gearcase, as I did, do not panic! Just remove the fan and the gearcase cover, retrieve the key, and it's actually easier this way as you can now aim the gear without a mirror over the shaft straight on, just more time consuming.
Bob in Sacto