Another thing to check out...
The rear shose friction thickness and the star adjuster...both has to do with it's "reach" to the drum
Also, consider using a fine wire brush to clean off the adjuster threaded rod. I usr a welders brush...looks like a giant tooth brush...first spray the threads with WD40 or some such. Key 2 things this does is to remove all buklt up roas crud...that jams up the nut...so it won't bind and freeze itself to the rod....and...lubes the mating nut to thread
Oh...they used to sell a clamp that decreases the cable lenght...puts a bend into the cable. Contacts the cable in three points....center pulls the cable while rge two other pionts keep the cable straight