Small holes, tears. Steel-wool surface and smear on plastic aluminum.
Large holes, tears. Cut a patch out of aluminum sheet. Steel-wool area around hole and underside of Satch. Spread plastic aluminum on ashing and embed patch in this.
Chimney flashing buckled or loose. Force together seams that have come apart, crimp edges, and seal with plastic aluminum. If metal has pulled loose from mortar joints or mortar is crumbling around metal, clean out the joints. Force aluminum back in place. Fill joints with caulking compound or asphalt roofing compound.