I've had my SPD touring shoes for about seven years. The cleats are the originals and are now quite worn and I noticed recently that one of them (not pictured) is at a rather wacky angle that can't be doing my pedalling action any good.
As the shoes are more or less OK, I'd like to replace the cleats.
The problem is that the cleat bolts (hex-shaped) are jammed with grit, mud, stones and whatever else I've walked on in the past 7 years. So the allen key won't go in.
Last night I tried picking the dirt out with needle-nose pliers, chiselling it with a nail and hammer and even resorted to trying to drill the bolt out. This last attempt barely damaged the bolt, but heated it up so much the bottom of the shoe started to melt.
Is there any way to prevent this from happening or to fix it when it does?