Dear Kris, I would check a few things that could be causing the problem. Be sure the brown tips are not being caused by spider mites, they really go after brand new terminal growth and the other is to examine the root ball for roots that are circling the pot at the bottom and not allowing the cactus soil to drain properly. The soil remains wet too long and actually prevents the roots from moving water up and into the plant. Another is the level of nutrition you plant has been recieving. Too much fertilizer will burn the roots and cause the symptoms you are seeing. New growth is impacted because the fertilizer salts are literally burning the roots. Assuming good soil drainage, you can flush out the salts with a through watering and be sure to empty the saucer so that salty water is not taken back up into the pot or better just do this in the sink or bathtub if it is a big plant.
Sincerely, Richard Hentschel
