I don't have a Janome, but your manual says you have a button to raise or lower under the needle arm, down under. Have you tried that?

Wow! 200 quilts....all done on the 4900? Both your feed dogs and walking foot could be worn out.

My first thought was the feed dogs themselves. I have heard of them being so worn that they need to be replaced.

I had to buy another walking foot after making lots of quilts. My first one quit feeding the fabric through.

Yes, 200 on the 4900......I am a maniac when it comes to quilts. (Ask GAGA Smith and Sharon) If it is in fact the walking foot feet, I will kick myself as I could have purchases a couple more when they were 75% off when a store closed. Barny, I am not sure about the "button" to raise or lower.