I purchased an old used ebike recently and was initially excited that it had front suspension. On close inspection though I've discovered that the suspension appears to be broken. The sliders (bottom part) don't move relative to the stanchions (chrome part). Can this fork be repaired? How? Or is it a lost cause?
That’s an interesting set of forks in that they are US made (or maybe just US branded). Inside the fork will be a steel spring or an elastomer (rubber) and maybe some simple form of damping. You can possibly restore them with some light sandpapering and some suitable grease.
The lowers (black part) will attach to the legs (chrome bits) with bolts either at the base of the leg or under the caps at the top of the legs. The caps look like they are friction fit from the little notches. You can insert a screwdriver into to gently lift them off.
Once you have removed the lowers you can clean everything, re-grease and then put them back together. The rust at the top of the leg can be sandpapered off with a fine grade sandpaper
If the spring is an elastomer the rubber has probably perished and will need replacement. At that point you’re out of luck. That will be a fork that wasn’t intended to be repaired.
At this stage you have nothing to lose by trying to restore them. If you fail a replacement fork of similar quality will not be very expensive. Your local bike store may have something secondhand.