I cant decide whether to cut my losses and sell now or take my chances, do repair and hope that it runs for another couple of years.even minor repairs on it have been expensive so I hate to think what the big repairs are going to cost.
Follow Pat F85's instruction plus push, pull, wedge up or down or various combinations of directions to relieve friction and let latch move freely. If that doesn't work, try to wedge a butter knife or something similar behind the part you circled in red. Start as far to the left as you can. You are trying to get it to retract to the right. When you get it open, replace the lockset and internals.
My jaw has done this for about 10 years. Dentist couldn't help (tried with retainer - but that was 10 times more painful). Still can lock a bit and makes a crunchy noise when I push it to the side but doesn't hurt anymore. I would recommend talking to your doctor if it's really painful.
