If amount of GHs is decreasing i have to hire technician or i can fix it by myself? and is it difficult?
You have to hire a technician to do the job for you, you can't fix it your self...You could also rent a technician from the employee market for an hour to do the work with a lot lesser fee than buying a technician...it's very easy, upon repair, the miner will be switched off, so when the repair is finished, all you have to do is to resume the miner