Try going up one size on the fuse (ie 20 to 25 amp) - sometimes as a system ages it draws more current than it was designed to - usually going up one size on the fuse will not endanger the wiring to the point of destruction. Most wiring is designed to carry more amperage than it is traditionally fused at. If you install a 10 ga wire traditionally rated at 30 amps, today's improved insulation will let that wire safely carry 40 amps. It's not the wire that's in danger of failing, it's the insulation.
Shop Owner and Mechanic with over 50 years experience