Ride, Wrench, Swap, Race
Join Date: Jan 2010
Location: Northern California
Posts: 9,194
Bikes: Cheltenham-Pedersen racer, Boulder F/S Paris-Roubaix, Varsity racer, '52 Christophe, '62 Continental, '92 Merckx, '75 Limongi, '76 Presto, '72 Gitane SC, '71 Schwinn SS, etc.
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I hate to have to remove screws whose adjustment is secured by the holes in the plastic biscuit, since the plastic won't grab the threads well any more.
But the biscuit could be replicated using plastic stock.
What might be needed here is to run a drill bit into the recesses that the screw heads sit into. Who knows what sort of detritus/corrosion might be in there preventing the screw heads from descending.
But normally, all that is needed is to flood the recesses with WD40 and work the screws down, cutting through the slurry.
EDITING:
One more thing I would check here is whether the tips of the screws have perhaps dug significant divots into the "stop lugs" on the pivot knuckle of the main arm. If enough alloy is gone there, the screws might not do their job.
This hopefully could be done visually, without removing the cage and arms from the pivots, by observing this area while moving the lever.
Last edited by dddd; 07-27-20 at 01:28 PM.