Loosening that screw a bit did help. I actually find squeezing his pelvis to be a much easier method of pulling those joins out, but I suppose there is a risk of paint damage if you do it that way.
For old times' sake, I got out my MP05G and transformed him out of gun mode. There's no doubt that MP05's gun mode is vastly superior to MP36's. There's no contest. Aside from one part on top that just doesn't want to tab in properly, MP05's gun mode is amazing. Robot mode is a different story, haha. You can't play with MP-05. At all. MP36, on the other hand, actually feels like a nice toy in robot mode. I also forgot what a mess MP05's legs are in robot mode. I like the transformation process of the legs, but the finished product leaves a lot to be desired, and a few bits just don't like to stay tabbed in properly. MP36's leg transformation might be the pinnacle of Transformers transformations though. That's a stunning process. I love it so much.
At the end of the day, I think both bots do things better than the other. I still really like the floppiness of MP05's transformation, which is reminiscent of the original toy's transformation. I really like how everything swings around. You don't get that with MP36, where every part of his body feels very distinct and separate from everything else. I like how MP05 looks as a bot, but as someone who likes to fiddle around with the toys, MP05 is basically untouchable in bot mode, though I still find his transformation very fun.