ABS hydraulic pump question

[spdrcrbmw]

Had a question about my M3. The car had been sitting through the winter and had only been driven 100 miles in the last year. Took it out this summer and the brakes were stiff and wasn't braking well. Decided to get a brake flush and fluid change (I've owned the car for 2 years and hadn't done it yet). They could not get fluid to bleed out the driver's front wheel or back wheel. ABS light came on at this point. We replaced the brake lines to stainless steel and were able to get fluid to all but the driver's front wheel. He suspects its a faulty ABS hydraulic pump. He said he didn't see any obstructions. As you can guess from the post, I am not knowledgeable in these things and not a DIYer and just had a few questions after searching the forum posts on related issues.

1. Does the problem sound consistent with a faulty ABS hydraulic pump? i.e. if i can get a used one to replace it should it fix the problem?
2. Is this the issue I've read about with faulty wiring that people are repairing by soldering?
3. Looking for used part (part #34512227216) is a bit challenging, any recs? http://www.car-part.com/cgi-bin/search.cgi should i call and just make sure the part #'s match up?
4. Does the brake master cylinder need to be changed?

appreciate any info/help in advance.

[MarcoZandrini]

Not being able to get fluid from
A caliper’s bleeder can be caused by several things:
- brake line is blocking the fluid
- the caliper’s fluid pathway is blocked
- the bleeder screw is blocked

The abs system doesn’t control the fluid pressure to the caliper. That’s the job of the master cylinder. The abs system pulses the pressure to each caliper when needed. It does this by rapidly activating/deactivating the individual brake’s accumulator.

I’d remove the bleeder completely to clean it with CRC Brake Clean. I’d then gently push the brake pedal a few mm to see if any fluid comes out off the caliper in question.