After a number of years, your metal gutters may need to be refurbished to keep them functioning properly.
Metal gutters may get small holes and punctures over the years. If this happens to your gutters, you may try patching the holes.
Make a patch by cutting a piece of metal flashing larger than the hole with a pair of tin snips. Cover the hole in the gutter with roofing cement. Feather the edges. Bend the piece of flashing so it fits the gutter. Embed the flashing into the cement.
Use pop rivets to secure the patch, and be sure to use enough caulk that it covers the patch and oozes out on each side.
If you have just tiny holes in the gutter, use a caulk gun and pure silicon caulk. Thoroughly clean the area, then on a dry day, apply the caulk into the hole. Fill the hole completely on both sides and let the caulk cure. Alternatively, use roofing cement. Feather the edges.
If your metal gutters are whole, just looking a bit worn, try a paint job. Scrape and sand off any flaking paint. Scuff the metal underneath with the sandpaper.
Apply a good metal primer to the entire gutter. Then paint the gutters with a quality exterior trim paint. With an excellent paint job, the gutters should last for months.