Cleaning the Canon 135 shutter curtains

Hi everyone,
I found a Canon 50e with a battery grip for a cheap price and bought it mostly as a spare for spares. The back cover is broken, and I paid €15 for it.

That said, it seems to shoot normally, but I'll have to test it with film.

I did notice a bit of dirt, perhaps it's the notorious sealing glue that can come loose after many years:



What would you use to clean it, and is it worth it?
Cotton swabs plus isopropyl alcohol?
I obviously have to be very gentle, I know. Could I also use those things used for cleaning the sensor?

I wouldn't touch that at all, at least not yet. First test the high speeds to see if there's any capping (partial exposures with a horizontal band remaining unexposed on the film). If not, use it some more; if there's a problem, it'll get worse over time and you can always look into it by the time it's necessary.

That looks like the very start of canonitis, not bad at all yet. My EOS cameras all have it worse. Try the highest shutter speed in both landscape and portrait orientation on a flat background and you'll see if you have a problem.

Don't use cotton swabs, small strips of paper soaked in isopropyl is the normal advice, but I doubt you have a problem from it.