For $29/mo, we provide access to advanced level technicians who will answer your questions on any Macbook board related matter to the best of their knowledge promptly & walk you through how to solve your problem so you can deliver a working board to your customer.
Internal speakers (left and right) work fine, not muffled at all. The only issue is the left headphone not having full volume--it does work, just very, very low volume (~10%). It's very similar to when an amp blows/fails, how you can still hear the volume, but it's super low. I hope that makes sense.