Scanning Dirty Slides

Could you help me out with a problem?

Recently found some old slides in a drawer and they're a bit dirty. I've cleaned them up a fair bit but stubborn spots remain.

When I scan these the scanner seems to focus on the spots resulting in OOF images.

Here is a sample

Byte size: ZERO | Content warning: NOT AN IMAGE

I think that scanners have a fixed focus. You may have to flip the slide upside down to get it sharp & then flop it back in PS.
Don't you have one slide that you know is sharp to test?

Try a soft artist's brush first. Be careful with canned air as it has a lubricant, so don't shake it up.
I wouldn't try film cleaner except as a very last resort. It's easier to PS out dust.
Some scanner software has built in dust removal.

Thanks, never thought of flipping the slide over

What scanner are you using?