Machine Head Wobbling

Hello everyone,
While cleaning the fretboard without strings, I noticed that two of the tuners in one of my basses (Yamaha trbx 174) wiggle a little, while the other two seem quite firm. Is it expected behavior? If it’s an issue, can I fix it myself?
Thank you as usual for your insight!


Show us the other side so we can see what’s holing the tuners to the neck. You may need to tighten them.


The wobbling keys are the E and the A, although with the strings in tension they seem to be still now… The other two were firm already without strings.


You should be ok.


Obvious question but have you tried tightening them? This is very common bass maintenance. Something good to check every string change in fact.


Hi Howard.

That was the first thing I checked. The screws behind are OK, but differently from other basses, I don’t have a screw in the middle of the peg I could tighten, so I posted the photos, because maybe I would have to open the machine heads behind to check for the cause of the wobbling.


how about the nuts on the pegs? Those often come loose.


The pegs themselves wobble a little without string tension, but it’s only two of them, so I thought there was something wrong with them. I am not sure what you mean by nut in that context?


Ahh - just noticed, your pegs are held on by just the screws on the back and only have a bushing on the front.

Many instruments have nuts that tighten down the tuning pegs around the peg shafts on the front. Yours does not.

Next thing to check, then, is the screws holding the machines to the back of the headstock.


Take the four screws out that holds the tuning machine in place. Pop the cover off. To where you can get to the peg, and gear. The four together off my Harmony H906 is basically the same as what have. The 6 on my Mini Stratocaster again is basically the same as what you have. Take them apart, clean them up, and put back together again. Be sure to tighten up the center screw holding the gear on.


Will do, thank you for the advice.,

How tight should the center screw be?

My Harmony, my Rogue SX100B, my Mini Stratocaster, and my Walmart special First Act ME80. All have basically the same exact tuners. I’ve actually got two sets for my generic Pbass AKA Rogue SX100B. I prefer them better than the other style. Where you have a nut and washer in the front. Keeping the peg in place, one tiny screw holding it it to the back of the head. With one tiny screw holding the top part to the tuner itself.

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