I'm thinking  'new boxes'  are  the way to get more money out of a  customer.   I dunno.  I've never  pieced one out;

Switches and contactors,     no doubt the lid or  dome  may be  pretty crispy/cracked, wear on the arm/linkage etc...       or  buying a  'complete'  ready to install and wire  box may be  just as  cheap $$ and time wise as  taking one apart,  and  freshening it up.  

I have  a couple  pivots  that  are  'close' to this stage in their  life too.

One thing to  consider...  say  I  fix  up a  30 YO  system,  that has not perfect, but  very good  pipe, been  recently  re nozzled,      do I  put the big dollar  oem  boxes  and  drivelines     expecting another 30 yrs?  or    put in the  aftermarket and  get  maybe another 10+ yrs?     I'm going aftermarket.   

 When I   trade it/ salvage it  THEN,  nobody will care  what it has  for boxes