Yes, that's correct! A 51% attack can be a serious threat to the security and integrity of a blockchain network, and it's important for miners to take immediate action if they suspect an attack is taking place. As you mentioned, some steps that the miner could take include stopping mining until the issue is resolved, notifying other nodes on the network about the potential breach so other miners can also take action to secure their systems, working with other miners on increasing computational power in order to counteract any attempts by attackers to gain control over more than half of it.

Additionally, implementing additional security measures like two-factor authentication (2FA) or cold storage options such as hardware wallets can help protect against further damage. It's important for all members of cryptocurrency networks including miners, developers and users alike- remain vigilant against possible attacks in order maintain system integrity and protect valuable assets from being compromised by malicious actors seeking personal gain at your expense!