Has anyone ever rebuilt a 240 brake junction box? I just replaced mine with a new unit, and would like to restore the old as a spare for one of the other Volvos in my keeping. I assume I can easily replace the 2 O-rings, one of which was evidently the leaker, but am more concerned with the condition of the bore. Can't see any obvious pitting, though there was some grunge just beyond the bore, where the chamfered shoulders of the big end-bolts touch, also some varnish-like deposits on the sliding contact piston. I expect scrubbing and swabbing with a good plastic or copper borebrush and brake cleaner might work, though I've never tried it. Hardly worth the trouble? Thanks!!