On the rear of my newly aquired T-Maxx, when I push down, the shocks compress but do not rebound. I assume this is not a good thing? What would be the best option here? I heard they can be rebuilt? Or should I just replace? I also read the an upgrade would be to replace the two Maxx shocks with a single buggy shock. Is this a direct replacement or will I have to modify or replace the tower? Thanks again for any help. You guys have been great so far.