Since no one replied I decided to just give things a try. First, I tried putting it in front of a heater vent, didn't do anything. Next, I tried a heat gun.
View attachment 54694 base spider on left/heat gunned spider on the right (note the shortened front legs on the heat gunned spider)
Test spider is on the right. While I was able to repose the front two legs the problem is that too much heat causes the plastic to shrink quickly and drastically, his two front legs are much shorter then the unmodified spider as a result of the heat. The difference between being poseable and shrinking is pretty narrow and if you stop the heat when it starts being poseable it almost instantly hardens again so you have to move things while the heat is on it. It's a very hard and unforgiving process.
I then tried using hot water. Like the heat gun, as soon as the spider is removed from the water it hardens almost instantly, so heating it in water, taking it out and reposing isn't viable. While in the water though it will get hot enough to repose, I just had to do all the posing under the water while it was boiling (or near boiling.) Very hard to get the right angles on the legs under water but essentially it worked. The other problem is that some parts seem to have slightly shrunk (the 2 fangs is where I noticed it was more then just reposing causing the problem since I didn't move them and no warping from reshaping occurred.) So not really a viable method on most things. I tested the water on a 2nd model that hadn't been exposed to the heat gun and had the same result.
View attachment 54695 Spider after boiling water reshaping
After all this I also tried just putting a dab of plastic cement on the bottom of a joint to see if it would be enough but it wasn't, the amount of cement needed would just destroy the leg.
