S60 Brakes Stuck occasionally - 2007 S60 2.5T

[VeroS60]

The MC rod not returning all the way makes sense. Presumably this would be caused by the rod on the booster getting stuck? Could this be due to lack of grease around the booster rod seal (under the boot in cabin)? I could check this before embarking on booster replacement but I read somewhere that is a special grease? Never thought to pull up on the pedal when the problem occurs... BTW, reasonably sure all parts are original so don't believe it could be a problem with MC or booster rod length. That car does have DSTC (confirmed by option to defeat it in menu activated by left stalk on steering wheel), and I see the two additional ports on bottom of MC - they look to be some type of sensor with wires attached. Trying to decide if I should replace the booster myself or just pay the man ($915). I've done some work on the car myself (pads/rotors, lower control arms, front struts, remove throttle body to clean) so I'm familiar with pain and suffering. I'd probably go with the ATE unit from FCPEuro ($218) as I understand that is OE (any thoughts on that?), but I've read the booster rod length could be different from true Volvo unit (any adjustment on the booster rod)? I'd also be tempted to go ahead and replace the MC (100k miles) and certainly if I find it's leaking when I remove it from booster. Will I have any additional problems due to this car having DSTC? e.g. bleeding brakes or removing the DSTC sensors from MC? Any tips on how to get the connectors off the sensors on the bottom of the MC? Thanks all for the comments.

[VeroS60]

So I finished up replacing the brake booster and MC this morning. Hopefully that will cure the problem with RF and LR brakes getting stuck occasionally. Bench bleed the MC off the car and then on the car at MC connections, and then all 4 wheels using a Motive pressure bleeder. Pedal seems pretty firm but perhaps a bit more travel, but that could be due to the new ATE booster vs original Volvo unit. All in all quite a bit of work but definitely doable by the DIYer, with a little help from the forum.