Corrosion inside Apple Watch - track the band slides in to

The track where the band slides in to my Apple Watch is corroded or something on one side of the watch! I had a lot of trouble removing the band but eventually got it off with a lot of brute force. How can I clean up the corrosion inside the track? (and yes I will throw away this band). I tried water, rubbing alcohol and lemon juice using a tip to get into the groove, but not seeing an impact. Any ideas? My watch is the series 5 aluminum. Has this happened to anyone else? Suggestions?