There is a long, thin piece of steel that rides on a ball bearing and is used to retract the blade guard when you lower the cutting head. Over time, this arm can deform very slightly where it rides on the ball bearing, making it difficult to lower the blade. I had this happen on my Kapex and tried to repair it myself. There's a lot going on in there, and I ultimately ended up sending the saw in to Festool for repair.
Does this at all line up with what you are experiencing?