NAD AV316 Surround Sound Amplifier repair

[bothaa7]

This amp of mine's Thump relays intermittently disconnect the speakers, when increasing the volume sometimes reconnect a speaker otherwise by switching between speakers A and B would do the job or nothing helps. Previously (years ago) I have replaced the relays or cleaned them up but now I cannot find the correct relays. It is a 24VDC / 5A / 2 pole / NO relay with coil resistance of 820 ohm. The coil resistance seems to be the problem due to the fact that I replaced the relays with coil resistance 1Kohm and now the amp remains in Protected state. I guess the resistance is to big and the relay actually doesn't actuate. The old relays cannot be opened up thus I cannot clean the contacts. Any suggestions or advice where I can find these relays. I tried RS Components but cannot find the correct coil resistance relays. Pls advise, thanks