[Milsurplus] R 391 autotune question

[Boeing377]

I just bought a Collins R 391. The prior owner never operated the autotune system. I have been operating it without motor tuning but want to explore that option soon. I remember reading somewhere that you can really mess things up from merely front panel operation if you don't know how to operate the autotune correctly. I cant seem to find the article when I search now. Does anyone have advice? 

Would I be better off operating the 24 VDC tuning motor on reduced voltage to prolong life? Any other 391 tips? 

I have been using the 391 with an early version Sherwood SE 3 outboard synch/product detector which makes it a very sweet sounding radio on AM and SSB. The Sherwood came with the radio as a package deal. I never would have paid what Sherwood gets for these boxes (now $695) , but I sure cannot compain about the performance. Its ability to lock onto and hold a fluctuating carrier is really impressive. SSB audio is waaaaaaay better than just using the R 391 BFO. SWBC AM signals sound unbelievably good even when fading. Sherwood really nailed it. Way better performance than the synch detector on the Sony 2010 which is the only other one I have used. 

I now have an R390A (EAC), an R391 (Collins) and an R392 (Stewart Warner). No R 389 and no plans for one. Speaking of R 389s, what were they used for? RTTY? Shipboard rcvrs?

Although I have drooled over Rick Mish's super duper OH'd 390s and 390As, my approach is very different and far cheaper. I get them working, spend an hour getting the front panel very tidy, repainting knobs if needed and then just pretend the innards are shiny and new and fastidiously aligned like a Rick Mish version. I'd love to have the amazingly light KC tuning torque that Mish can achieve, but it's beyond my pay grade (lube lightly and forget about it). I look at my 390 class rcvrs as wrist exercise machines and they perform that function quite well. 

73
Mark
AF6IM
www.parachutemobile.org