If you see the innards, you realize the weakened rubber grommet is more critical than many think.
the link you posted is terrific, repeated below, and 2 links found within it https://www.audiovintage.fr/leforum/viewtopic.php?t=55306 http://www.ne.jp/asahi/moto/jogging/audiowood.html http://www.ne.jp/asahi/moto/jogging/audiowood.html#7045
the top link photos are the best I’ve seen, especially when fully disassembled to see the internal brass piece separately.
my 7082 was slightly different, however,
I now understand the design, which does TOTALLY isolate the rear assembly from everything forward of the pivot via a ’ two stepped’ rubber grommet:
’two stepped’ rubber grommet: like a 2 layer cake, the top layer (forward-invisible inside the tube when assembled) is a smaller diameter than the bottom layer (rear-visible separates the front and rear tubes when assembled).
It is the deterioration of the smaller unseen portion of the grommet that ’allows’ sag of the rear assembly. When seriously degraded (as mine was before the seller repaired it), it ’allows’ serious damage to metal parts.
The smaller diameter rubber layer gets pushed inside the forward tube, thus unseen when assembled. That is the TOTAL isolation from the front assembly. That portion, unseen, must be firm enough as it is carrying all the weight of the rear assembly.
The larger diameter rubber layer is the diameter of the tubes, thus visible, and simply keeps the tube faces apart from each other when assembled, like the white part of an Oreo cookie.
The larger diameter portion of the grommet also restricts forward movement of the internal rubber.
When the larger diameter portion is deteriorated, it also ’allows’ sag, however, it is the unseen rubber that is most important.
1. rubber grommet slides onto the brass fitting. The brass fitting has a thin flange at the face toward the pivot. That simply stops the stepped rubber piece from moving further forward.
2. Insert the brass piece/forward portion of the rubber grommet into the hole in the rear face of the pivot. Position it back far enough so the brass flange (now unseen) does not contact any internal pivot parts (in any position when the arm is moved.
3. Tighten the set screw.
4. The threaded shaft of the brass fitting faces rearward. The larger diameter portion of the rubber grommet is in place.
5. spin the entire counterweight assembly (it has internal threads) onto the threaded shaft. spin forward until it’s face is firm against the face of the rear face of the rubber grommet.
6. Fasten set screw.
Serious Internal Damage:
IF/When the interior unseen rubber grommet sufficiently deteriorates, the sag allows/moves the forward flange of the brass piece too far forward, actually making contact with metal within the pivot.
Half of my brass flange was missing, (fell out when seller repaired it). The remaining portion of the flange was ’mangled/misshapen-ed’. It must have been making seriously detrimental contact against internal pivot parts.
Before serious internal damage occurred, there had to have been minute contact, minutely effecting pivot movement, and both progressing speck by speck.
You can buy an arm that has been repaired, and not see/know of any past or potential internal metal contact. Circumstances, curiosity, nothing to lose led to me discovering damage within. And, a set of tiny allen wrenches.
I suppose seller, when repairing the rubber, might have ’re-set’ the fitting rearward enough that no internal contact was occurring. All might have been happy ever after, but it was a disturbing sight for sure.
Anyone making the repair can re-set the brass piece to avoid internal metal contact.
Mostly or Completely remove a damaged brass flange? I suppose so, however, it would have to be a one piece stepped grommet so the larger diameter layer kept the attached smaller diameter internal layer in place, unable to move too far forward. Careful positioning of both fitting and rubber in the pivot then locked with set screw.
After seeing this, I would say, if your arm sags, fix it.