My tradition of turning routine maintenance into bloodsport continues as I am trying to change the brake pads on my 240D. I cannot, for the life of me, get the retaining pins out of the caliper. I used a punch and hammer and couldn't get the top one to budge ... the bottom one budged about a millimeter and no more. It's like they're welded into the caliper. I tried putting some wd40 on them but that didn't do a thing. Any tips on loosening them up? Heat them? It's pretty cold out and I'm guessing that doesn't help. The calipers themselves don't look too great so maybe I have to replace them anyway, but I'd like to put some new pads in and see how it goes (I already flushed the brakes + clutch and that went OK).

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1987 300D, arctic white/palomino--314,000 miles
1978 240D 4-speed, Euro Delivery, light ivory/bamboo--370,000 miles
2005 Jeep Liberty CRD Limited, light khaki/slate--140,000 miles
2018 Chevy Cruze diesel, 6-speed manual, satin steel metallic/kalahari--19,000 miles
1982 Peugeot 505 diesel, 4-speed manual, blue/blue, 130,000 miles
1995 S320, black/parchment--34,000 miles (Dad's car)