Getting out pencil injectors can be a horrible job. Sometimes they pull right out, and sometimes nothing will pull them out. I have had to pull a few cylinder-heads and drive them out from the other side a few times.
We had the special OTC puller at all the Deere dealerships I worked at and nobody ever used it. Using a good-quality "lady-foot" pry-bar that had a sharp edge that caught in the puller-grooves worked just as well.
I have no idea if injectors is your problem or not. I have done injector changes on a lot of Deere engines that were running fine, yet all the injectors tested bad.
In theory, the proper OTC slide-hammer puller that fits tight into the two puller-grooves is supposed to be best. Like I said, we did not use it since when we DID use it on very stuck injectors it just stripped those grooves out. The Snap-On lady-foot pry-bar is what worked for us. The same tool from Matco or Mac did not work. I bought mine 40 years ago from Snap-On and have no idea if they are still the same. From the photo, it looks like they are.
Make sure you use some anti-seize compound on new injectors if you put them in. It is amazing how stuck they can get.