I don't know that this is the right board for a question about stationary recumbent bikes. But on a regular two-wheeled bike, if I experience pain "between the mid upper thigh and the knee on the direct top, not the side", the first thing I would try is a higher seat position.

In the past, when I have had any sort of knee pain, I have raised my saddle, and that's worked (for me) probably 90% of the time. This is due to the misalignments that occur when I don't get nearly full leg extension. You want your legs to be extended something like 98-99% at the "bottom" of your pedal stroke.

This is pretty much the same as walking, where your legs are fully extended while you walk, but never hyper-extended. So I would move your seat back, or whatever you need to do in order to get full leg extension.