Knife bar on my Megado is getting stuck in the groove

The groove where your Megado knife bar travels can become swollen due to humidity or contract due to a dry climate.   This is simply something that can happen to wood.    Use some Sandpaper to smooth the groove and clear any debris that may have gathered (weaving dust) or simply make it a little bigger.

You can also use a Teflon Dry Spray lubricant - see this article General - My Loom Squeaks