Yeah, my green SDI passed on Saturday. But only just. The rear brake compensator had stuck, so on the brake tester, it indicated that the back brakes were faulty (like only half power- would not lock up). But on handbrake, they worked just fine and locked. The tester confidently said "yup, both your rear cylinders are shot. You need new ones. We can do it for you today...".
So I "humbly" suggested that it may actually just be a stiff compensator lever or stuck plunger. And that it'll be obvious when up on the ramp for the underside inspection. So once up in the air I had a look, asked if he had a hammer that I could borrow for a moment- gave the housing a thump, mentioning that may have sorted it.
Once back down, he tested it again and all good. "In 30 years, never seen that before. Know a bit about cars then?". I just smiled and thanked him, through gritted teeth. So he was going to change both rear cylinders (wrong) and bill me for £175. Yeah. And the compensator would have probably reset anyway when bleeding everything. SMH.
Get a sump plug with built-in O ring. You'll never need a crush washer ever again...