I've been a regular customer ever since your opening. And I'm probably one of the people who has played on your GuitarFreaks 11th Mix machine the most. Heck, I'm almost a Platinum member because of it. That aside, I would have to complain on how you take care of your machine. It's been over a year since you've had that machine, and ever since the strap on the left controller broke, you never bothered replacing it. All that you did was tie it up in a knot, disallowing late teens, such as myself, and adults to play the game due to the width of their developed torso.
Now, while I complain for the fact that you haven't bothered fixing it up to now, I remained a patron to the machine, using the right guitar controller even though its notes aren't audible. It's been more or less half a year since this problem, and I'm quite disappointed that just today the strap on the right controller has gotten the same sickness. How the heck am I supposed to play on your machine now?
I don't think it would cost a lot replacing the guitar strap. The Timezone branch in Mall of Asia resorted into replacing the offending straps with real guitar straps, making it even more comfortable than the regular one. Sadly, the said machine's right guitar controller has a hard-to-fix effector knob problem, and its picking lever has lost its ability to detect up-picks. You're quite lucky that the buttons and pick on your machine aren't that worn out yet, although they're starting to show their age.
And it's not only the GuitarFreaks machine. I've also noticed that every week after week, I ask you to replace the defend button on the player two side of SoulCalibur III and the kick button on the player one of the same machine after playing my free game and losing because of the said buttons. This has been a problem about two months since your opening, and until now, it has yet to be fixed. Also, the hi-hat on DrumMania 10th Mix requires a large amount of force in order to press, which would just cause more damage to the said pad.
If you don't have plans on replacing these machines entirely, at least do a good job maintaining them and replacing parts when needed.
tl;dr: Fix the damned strap on GuitarFreaks, goddamnit!