933G hydraulic filter replacement

This is going to sound dumb to all you old pros. But I want to change the hydraulic filter in my 933g. I read everything I can in the operators, service, and parts manual. Followed all the steps. But after all the bolts were taken off the housing cover is stuck and doesn’t come off. What is the best way to get it off without breaking anything?
The lid has three threaded spots that look like it’s made to use a puller. Is that for a puller? If so what type? Doesn’t really look like a pulley puller would work since the center is not hollow.
Thank you to anyone who can help. I want to get this old girl in the best operating condition I can.

My service manual  indicates later filters have three 3/8-16 threaded holes to be used for jacking screws to remove the cover.

Thank you Old Magnet. Last night I ordered 3/8 tap bolts to do what you said. It makes perfect sense now that you said it.