(ET) Intermittent no reverse on my E12

[Biophiliac <keljefs sbcglobal net>]

Hi all,
I'm a long time reader of this forum and have been getting some help from 
Jim Coate directly because I've historically been unable to post with my 
Android thingy and have no other on line options. Hope this works.

Among other problems,  my E12 intermittently doesn't move in Reverse. 
Especially after running awhile or more frequently with this record heat. 
I carefully removed  and swapped/switched out the reverse switch with a 
forward one . Didn't solve. Any ideas from those viewing this forum would 
be welcome.
Jef Spalding