Never noticed until now that the rangefinder is also missing the SX-70 greeble for the Slave 1 scene. Can't believe they took the time to glue it back on or put on a new one.
Anyway, on topic, sadly this example is for the outside of the rangefinder not the inside but I think it still illustrates a valid point.
When Boba is in the cockpit of Slave 1 we get a wonderful direct shot and it shows his rangefinder is dirty as hell.
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Then to support Fett 4 Real's comment, in the same shot when he starts to turn away nearly all the weathering is suddenly washed out when the lighting changes and a light shines right on it. In the behind the helmet shot of the bridge the light appears to be shining directly onto the stalk.
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So while I won't say they for sure didn't add more weathering during/after production (because they added the gray splotch to the gauntlet during production and SE has all kinds of additional stuff decades later) I will say film sets can wash away a lot and that's worth considering. Also, the PP3 stalk is much cleaner - could they have swapped stalks at some point?