Front Brake Caliper guide pin play?

As long as you have free movement of the pins, I would not suspect any issue there. I would look at the condition of the rubber brake hoses. They may look ok on the outside, but the inside tends to break down. This causes the hose to act like a “one way” valve. I’d change both hoses simply due to the age of the car. People tend to think the rubber hoses last forever, and that is not the case.

 

welcome to PC
I haven't done any brake work for longer than you've had a look at yours and none yet on a prii. So I'll try not to give any suggestions about the slide pin thing or the uneven wear. Hoping one or two of the experienced gen2 3 members will see this and comment.

One thing I think will help, describe the uneven wear issue. which wheel(s), which tire surface(s),
and how long you've noticed the slight pull to the right. Did the pull start before the alignment? Did you get the alignment for an issue you noticed or on a mechanics recommendation and where was the work done if you feel like adding that info.

Great question and best of luck.
I found this thread from your other post in Intro new.

 

The slide pins aren't subject to very high forces: the forces of braking go directly from the pad edges to the beefy caliper mounting bracket, which is solidly bolted to the knuckle. The guide pins are basically there to make sure the caliper stays with the car when you go places. As long as they move freely, slight play in them is of no concern.

 

Old thread, new comments - probably mostly useless for most others here, but after replacing my front pad and rotors I still had questions about the caliper mounting bracket and the slide pins.
Yesterday I changed oil and pulled the caliper, pads and rotor on the right side and did a wash down of the caliper bracket and slide pins with hot soapy water getting ALL the grease off both of them. It was around 9pm and the batteries on my headlamp flashlight were almost fully discharged and I brought the caliper bracket and slide pins inside to work on them in a lighted warm area. I hadn't replaced the slide pin boots or the lower slide pin rubber ring while doing the initial work on the pads and rotors. But I still wasn't comfortable - due to the extensive wear as 35k of the inner pads and the condition of both front rotors - with my understanding both upper and lower slide pins and what made them feel so tight in the caliper bracket guide holes.
Anyways, while still outside I couldn't get the lower slide pin in the guide hole without it either sliding all the way up the slide pin or - if I got it in the guide hole while in the pin groove for it, the rubber would lay in the bottom of the guide hole after I'd moved the pin in and out a few times.
Inside the hot soapy water wash - as per techstreams alternate suggested way of rebuilding the caliper - I still had issues. I pulled the silde pin boots and lower slide pin rubber and replaced with new this time. But it didn't make much difference in the tight - to me - fitting slide pins, even in the warmth inside. The reason, the slide pin boots are a really tight fit on the pins where the boots sit in the caliper bracket, for what it's worth.
The other question I wanted to know about was the possible differences in the upper and lower slide pins. Without boots or lower pin rubber and bare metal - all grease removed - I dropped each pin in the other guide hole. Sure enough, the top slide pin is longer than the bottom slide pin, 1/4 inch maybe, but different enough. There was also a LOT of wiggle room in the guide holes with the pins dropped into them with no boots, lower pin rubber or grease. Significant in my mind anyways .... but my concerns are probably overstated by what I saw when I removed the OE parts.

 

It's kind of a design-fail, that the two pins are slightly different lengths. I wonder if it could be put together with the pins reversed?

 

I think it could. The boots would look a bit off, but I think it would be possible. I checked for markings on the caliper bracket and there are about 6 or 7 . The only ones I understand presently are the two R 's.