The other day, when I was extremely busy, a customer came in saying "my gears aren't shifting right, can you take a look?" but I had to turn them away because I was so swamped.
If I keep accepting walk-in repairs like this,
I can't make any progress on wheel builds or component assembly.
But since they said they'd "wait," I did what absolutely had to be done
and took a look at what was going on


↑A guide pulley on the bottom (and the type that has necessary play)

↑A tension pulley on the top
That's what I found.
The customer said they hadn't touched anything,
so this is clearly some crappy shop's mistake from somewhere.

But an even bigger screw-up was that the rear derailleur is an RD-7900 Dura-Ace,
and according to the customer, they recently had the pulleys replaced at the shop.
They'd asked the shop to "use Dura-Ace pulleys,"
but instead, lower-grade metal-core
bush-type pulleys were installed on both upper and lower.
I didn't realize until I pointed it out that they didn't have the actual Dura-Ace pulleys.

For what it's worth, I checked and the 7900 pulleys are still available for purchase.

The gear shifting problem wasn't mainly caused by the pulleys,
but the work still ate up about as much time as it takes to build one complete front wheel.
Please, just give me a break.