Conference vmszoo::rc

    Don't know about 133's, but I've had the same problem on Futaba 128's,
    and it was always a dirty feedback pot or wiper, or the wiper itself
    wasn't contacting too well. In all cases a quick blast with switch
    cleaner, a wipe over and if necessary a spot of wiper bending and all
    was well.
    As regards the 'OK on throttle' bit, it could well be that it's not
    usually 'parked' in the normal neutral spot which is where most of the
    wear takes place anyway.
    
    Good luck,
    
    Malcolm

    You can still return it for service....  You just won't get the service
    for free.  Or I bet that the radio guy in Chelmsford would take a look
    at it...  Check with Tom's for a contact...
    
    jeff
    

    I've had many "jittery" S133's.  Sometimes it appeared that the
    hunting was worse on the bench with the Antenna of the transmitter
    retracted.  The JR 341's I am using seem better, albeit more expensive.
    
                                                     Regards,
    
                                                     Jim

    Thanks gents,
    
     One question:  Dirty feed back pot????  Where is it; could you
    describe.
    
    Also I have noticed that the jitter is worse on the workbench with
    my 347 antenna down. Looks like i'm not alone.
    
    thanks again for input.
    
    regards
    
    mike

The feedback pot is buried inside the servo. It's tied into the geartrain 
opposite the motor and lets the electronics know how far things have moved.
I've never opened the bottom part of a 133 case but I'll bet it's a 
challenge to get everything back in there once you take it out and clean it.
The ones I had in an older standard size servo were a piece of silicon with 
carbon traces on it and a set of bent metal wiper arms that made contact. If
the arms get squashed they don't make good contact. If they get oxidized they
don't either and the servo will hunt/jitter and momentarily make contact and
stop, lose contact and jitter again... The parts list that comes with each 
new S-133 has an exploded view which should show it and give you a feel for
how difficult it will be to do. You use a spray on electronics cleaner and
avoid getting any skin oil on the contacts (a pencil point or pin will lift 
the wiper arms GENTLY!)

    Jim,
    
    Thanks again

I've done this.  You need to get some pot lubricant from ACE RC;
they're the only folks I know of who carry it.  It is indeed a
challenge to get everything out and back in again.  Remove the case
cover and remove the gears.  There might be a problem in getting the
main drive gear off its shaft.  This is not mandatory, though it makes
for a better job.  Note that the main gear has some indents on it that
slide into a pin on the case and restrict its rotation to 180 or so
degrees.

Now remove the bottom of the case and unpack the servo board.  Move it
out of the way and remove the screws on the pot case.  You can get at
the pot now to clean it and apply a small amount of lube.

But now you have to reassemble the whole works.  If you've removed the
main gear, reassemble it to the shaft now.  Put the bottom back on the
pot case, keeping the pot arm pointing straight ahead (or backward in
some cases).  Connect the servo to your radio and turn on the TX.  The
motor may start moving in one direction or another.  Rotate the main
gear until it stops and very carefully reassemble the other gears in
the train.  Now you can finish the job by cramming everything back
together again.

As for your problem, it could be anything.  My luck in curing servo
problems by cleaning the pot is about 50-50.  Is it worth it?  Only
when its snowing outside and you have nothing else to do.

    sounds intimidating.....
    
    oh well, if i cant get 10 lbs of sh*& back into a 5 lb bag,
    it will be a low weight hand launch servo.
    
    
    thanks

Just keep telling yourself that you really wanted to remove the case to 
save weight and you'll do fine.

You should be able to use "tuner cleaner" on the pot. This should be available
locally.