I have had these two Langevin 251A program EQs for decades sitting in a box of dead gear. I picked them up from a studio in Hollywood dirt cheap about 24 years ago. They were in pretty rough shape, the covers were missing along with the freq selector knobs and one of the units was missing the machined aluminum pieces that hold the wipers to the traces on the side of the unit rendering it pretty much useless. I had Honey from the band Veronica Grim and the Heavy Hearts machine me some new aluminum pieces using the good unit as a template. Honey is a master mechanic with a very complete machine shop and a really good guy to know it you need a part that is obviously unavailable. Before this job he helped me fix an old fly fishing reel by making a part fit to another part properly. Anyway, I then cleaned them up which wasn’t easy. Spent hours with a pencil eraser cleaning up the traces. Finally, I pinned them out per the pin out screened on the circuit board and guess what? They work as intended and sound absolutely fantastic with zero component changes. They have only wire coil inductors, so nothing to really go bad in there anyway. . I’m using some Cal-Rec 1061 line amps to bring these passive Eq’s to line level. They have a wonderful top end for vocals, silky smooth with lots of air and the low end is quite musical as well. Glad I never threw them away or sold them for parts! The moral of the story is, never give up on quality crusty old vintage gear!