by Warkton Tornado No.1 » Sun Jul 18, 2021 4:32 pm
Wouldn't it be great if LCGB had a spark eroder for the use of all members, & all that would entail being a nominal fee with P&P costs?
I think you may be able to get quotations, but the cost prohibitive.
The alternative is to drill out the corroded steel screw remnants. With patience & care, it can be done.
Unless you are very steady handed & have access to an electric/battery drill that can go very, very slow, a pillar drill is best. I have got them out using drill bits in a Milwaukee 18v brushless Combi but that is one of the best hand tools TBH.
Beware centre dotting too much the broken screws or they work harden. Using good, fresh drill bits (split point are good) drill as slowly as you can with a good cutting fluid with, say, a 2.5 mm drill. If you are accurate, that can then be followed up with bigger drill bits until the remnants virtually collapse inwards. The fasteners are usually M5, so 4.2 bit is the largest size to go.
Follow up with a tap, or, if the drill wandered, get the holes Helicoiled.
Fit with replacement fasteners using Copaslip. The bottom holes that secure the mudguard can have (Copaslipped!) stainless studding with nyloc nuts/washers. The studs ensure that the full thread available is used. Much, much easier to fasten/unfasten & virtually future proof.
Good Luck!