The presser-bar lever is prone to damage since it sticks out. If yours is bent or broken, it can be replaced. The following shows a Necchi BU Mira, but it's essentially the same for Novas, Noras and probably other models as well. For BF (straight-stitch only) models, the principle is the same--you have to get the needlebar out to get to the presser-bar lever--but the mechanism is simpler, there is no "cage" to remove.
Start, of course, by taking off the extraneous stuff... needle, foot, thread cutter, and throat and slide plates.
When you take the faceplate off a BU (zigzag) machine, this is what you'll see:
As you can see, there is a metal "cage" around the presser-foot bar, that prevents you from getting to the lifter lever. So it's all got to come off.
Just so you can understand what you're looking at, the photo above shows the cage next to one in place. The presser-foot bar goes through the left, and the needlebar goes through the right side, and the whole piece pivots on the needlebar side when in zigzag mode.
The overall process is first to remove the presser-foot bar, next to remove the upper and lower collars that hold the cage in place in the casting, and then remove and replace the presser-foot lifter lever.
To remove the presser-foot bar, first remove the silver thread guide, which is held by two screws to the black block. (You can see the guide in the first photo, above.)
Next, remove the grub screw that is below the two screws you just removed. This is what holds the sliding block to the presser-foot bar, and is where you adjust presser-foot height and position.
One more thing to remove before you can get the bar out. At top, fit into a groove in the knurled piece, is a circlip. It's black in the photo below, above the "finger" and near the top of the cutout. Take the clip off. That's sometimes easier said than done.
Once that circlip is off, the knurled screw is released and you can screw it off the "finger" piece (pressure indicator) and slide it out of the casting. Note that it screws on and off *backwards* from usual, i.e., clockwise off and counterclockwise on.
Slide the presser-foot bar up and out, and collect the loose pieces (tension finger, spring, and cup at the bottom of the spring) from behind the cage. You don't need to take the black sliding block at bottom out, you can just maneuver it out of the way as necessary.
For the sake of understanding, the following photo shows the pieces that make up this assembly. Note the two collars at left. These install in the machine casting at top and bottom, and hold the cage in place. In order to get the cage out, these collars must be removed.
The upper collar is secured by a grub screw at the top; take it out.
The collar is flush with the top of the machine. It's likely stuck in there pretty good. I use Kroil to help break it free. If you like another product, use what works for you. In my experience, there is nothing better than Kroil, which is available mail-order from the manufacturer, Kano Labs. NAYY (no affiliation, yada yada).
I use a punch to slide the collar down and out:
The lower collar is also secured with a grub screw, this one is accessible through the light fixture if you have a long enough screwdriver, otherwise unscrew the light framework to get to the screw.
Again, I use Kroil and a punch to push the lower collar down far enough to release the cage.
The presser-foot lifter lever is secured by yet another grub screw, this one on the back and to the left of the lever. Take it out.
The lever is mounted on a pin, simply wiggle it out.
When putting your new lever in, be sure that the tension-release piece (black in photo below) is pushed up so the end rides on top of the lever, and isn't caught below. If it's caught below, you won't be able to push the lever flush with the casting. Once the lever is in and flush, replace the grub screw to secure.
Next, hammer (I use a piece of wood against the metal) the bottom collar back into place, aligning the cage and the black slide mechanism properly. Then hammer the top collar into place. Again, I use a block of wood to protect the metal.
Replace and tighten the grub screws to secure the collars, and replace the light fixture if you've removed it.
Clean/polish the presser-foot bar while you have it out. Then replace the spring with washer/stop at bottom, behind the cage. Move the handwheel as needed for easy access.
Slide the bar from the bottom up through the casting, washer, spring, and tension finger; you'll need to compress the spring to slip the tension finger on top of the stack.
Note the textured stripes on the bar; these are to position the height of the bar. The lower stripe should show through the grub-screw hole, and the upper stripe should be between the top and middle screws on the black slide block, and not show. The picture below shows the bar properly installed, with another one next to it to show the markings.
To set the foot position straight, install the throat and slide plates, and put a foot on the bar. Adjust so the foot is riding perfectly straight on the feed dogs, then recheck that you haven't moved the bar up or down, and secure with the grub screw. Note that this grub screw is likely to have a sacrificial washer in it. Others may as well, I've not found a lot of consistency in this, but often find them in Necchis. If you found tiny little discs when you took things apart, that's what they are.
Finally, screw the knurled screw on through the casting at top, remembering it's a backwards thread and tightens counterclockwise. Push down on it to put the circlip back in the groove, securing the piece and finishing the job.