Having read the many threads on Vitamix, we purchased a certified refurbished for Christmas. It is a "next generation" labeled a 7500.

The first time we used it, I smelled electrical heat.

Each time we use it now, the contents of the container are rising and falling as the motor speed rises and falls. It is about a once per second motor speed change.

One could imagine that the nature of the contents could cause the motor to load up, slow down, and as the contents are pulverized, speed up. However, with only water in the container, the same speed oscillation occurs. One might argue that the blades are causing a cavitation and momentarily speeding up through the void in the water, then slowing down as water hits the blades. It does it with ice and water in the container also. A faint smell of electrical hotness is detected with only water spinning around.

It occurs at all speed settings, so it is not resonance.

All that noted, my question is simple -- is this what I should expect?

It sounds like the motor or bearing has a lot of end play. I would get on the phone with vitamix. it is normal to have a little up and down movement, but yours sounds a bit excessive.

The motor speed should remain at the level set. I have a refurbished unit I bought 22 years ago. Only had to replace the blade set once.It has been a beast.

No electrical smell ever in mine.The one I have is a model 5000.

We have a Professional 750 model. It has 10 speeds, plus an automatic setting for smoothies and a bunch of other specific functions. On the auto settings, it will start on a slow speed, then gradually increase, but the speed doesn't rise & fall & I've never had an electrical smell.

It sounds like you got a defective one. Ours has been used at least two or three times daily since we got it about four years ago. I did have to replace the shaft & large nut on the container because it came loose & damaged the threads, but the thing's really been a workhorse.

quote:

Originally posted by jimmy123x:
It sounds like the motor or bearing has a lot of end play. I would get on the phone with vitamix. it is normal to have a little up and down movement, but yours sounds a bit excessive.

I second this recommendation.

That can happen if there's only a little bit of stuff in the pitcher, or if the stuff in the pitcher isn't liquid enough.

quote:

Originally posted by 4MUL8R:


The first time we used it, I smelled electrical heat.

A faint smell of electrical hotness is detected with only water spinning around.

The "electrical heat" you mention is actually overheating insulation on an electrical wire.

I would be asking for a replacement pronto.

Vitamix customer service reports that
(1) the faint smell of hot electric is normal for the first few blends, as the motor wires emanate some odor.
(2)The machine is designed to run at "10" and intermediate speeds are solely to ramp up, sweep through, and not stay running at some slower speed
(3)They will certainly make me happy under their incredible warranty, but recommend I take a few days to truly use the machine before asking for a replacement.

If you turn on the machine without the blending vessel in place, it makes no oscillation.

If you turn on the machine with the blending vessel in place, but dry, it makes no oscillation.

If you put half a carafe of water in the vessel, and turn it on any speed, it pulses the water up and down and seems out of balance. The entire blender is moving just a bit on the counter.

Make sure the removable rubber gear/plug (no clue the actual name) at the top of the base is fully seated.

Also be mindful of the order in which you put the ingredients in
Lighter ingredients get loaded first and heaviest last.

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