So what could happen if miners like you met with a serious repair problem? Do you just leave those gears aside?
Yes, sadly in most cases you just need to
throw them away, some issues can be fixed, but it all depends on the cost and the level of expertise it requires, since sending the gears back to China was never an option I had to learn how to fix at least some of the issues, whatever I can't fix I simply get rid of.
Isn't that a loss if the miners doesn't function properly?
That is a part of the risk that miners need to take, many of them don't add this factor in their business plan, this is why I have always said that miners' main focus should be quick ROI rather than long-term profitability since these miners can fail at any given second, even if sending the gear back to bitmain was an option, by the time you get a replacement difficulty would have spiked or/and the price would have dropped and everything you planned for is out of the door.
I don't mine nor I am technically strong in Mining, but going through the posts from Mining section urged me to ask a few questions to regular miners like you. AFAIK there are only repair centers in CA, Russia and Europe, so what happens to miners living in other geographical locations? Should they send back the gears to China and spend a hell lot of shipping charges again?
Most miners will run the math when it comes to sending those gears to the repair centers of Bitmain, if it's worth the fees i,e the mining gear is new and worth a lot - they would ship it, if shipping costs $200 and you need to wait for 2 months when it's only 1 bad hash board out of 3, and the whole miner now worth $500, it makes no sense to send it back to Bitmain, they will just unplug the bad board and mine on.