"Arny Krueger" said:

Generally, needle bearings are adjustable. The needles are threaded and
slotted for a screwdriver. Beware of over-tightening.

The bearings in a tonearm are relatively heavily preloaded by the weight of
the arm. This is not the front suspension of a car where the bearings can
have a negative load. Therefore, it generally doesn't matter if they are a
little loose, unless they get so loose that there are alignment or friction
problems.

Loose bearings will alter the resonance frequency of the tone arm, as
well as increase the amplitude of resonances because of ineffective
transfer of energy at the needle's points.

Generally, they can make a cart-arm combo sound like ****.

--
Sander deWaal
Vacuum Audio Consultancy

Sander deWaal wrote:
"Arny Krueger" said:

Generally, needle bearings are adjustable. The needles are threaded
and slotted for a screwdriver. Beware of over-tightening.

The bearings in a tonearm are relatively heavily preloaded by the
weight of the arm. This is not the front suspension of a car where
the bearings can have a negative load. Therefore, it generally
doesn't matter if they are a little loose, unless they get so loose
that there are alignment or friction problems.

Loose bearings will alter the resonance frequency of the tone arm,

No way. A tone arm is a classic mass-spring damper system. If the bearings
have too much friction they can contribute to the damper part of the
equation, but they aren't supposed to have appreciable friction.

as well as increase the amplitude of resonances because of ineffective
transfer of energy at the needle's points.

No way. The energy gets transferred the same because the normal forces
eliminate the possibility of zero or negative forces at the pivot points.
Basically, tracking force and groove tracking make only microscopic
contributions to the forces on the bearings.

Generally, they can make a cart-arm combo sound like ****.

High friction can make a cart/arm combination sound like crap, but I
already discussed the consequences and limits of that.

"Arny Krueger" said:

Loose bearings will alter the resonance frequency of the tone arm,

No way. A tone arm is a classic mass-spring damper system. If the bearings
have too much friction they can contribute to the damper part of the
equation, but they aren't supposed to have appreciable friction.

If you'd care to do some measurements yourself, you'd see what I mean.

as well as increase the amplitude of resonances because of ineffective
transfer of energy at the needle's points.

No way. The energy gets transferred the same because the normal forces
eliminate the possibility of zero or negative forces at the pivot points.
Basically, tracking force and groove tracking make only microscopic
contributions to the forces on the bearings.

When listeners all over the world report that using a different mat
alters the sound because of resonance control, what order of magnitude
of voltages are we speaking about?
Good vinyl playback IS about resonance control.
In the uV range, things like loose bearings count.
Viz the OP's question, and experience with vinyl playback by thousands
of enthusiasts, like myself.

--
Sander deWaal
Vacuum Audio Consultancy