Definitely use the money toward something new and do not repair what is now an obsolete AVR. Most mainstream electronics, especially AVR's, are not worth repairing as the technology changes so rapidly.
Modern AVR's now offer lossless decoding of DTS Master and Dolby True HD, the two sound formats found on all Blu-ray releases. Also up to 7.1 channels of uncompressed audio and video can be carried by one HDMI cable, greatly simplifying the HT tangle nightmare of years ago. These two key features are something your old AVR does not have and why you should consider a modern HT receiver even if your old Marantz was still functioning properly.
Regret to advise that IMO, you will not get the same quality or power as your old Marantz for $500 or even $800. You will get more features. So if sound quality is paramount, make sure you get an AVR with a full set of pre-outs. If you find the internal amps of the AVR are not cutting it, by having a full set of pre-outs, you can consider adding an external multi-channel amp. But try the internal amps first - that may be all you need.
So without recommending any of the mainstream brands you mention (throw Pioneer Elite in there too), I just want to put forth the above caveats and strongly advise you only consider a model that has a full set of pre-outs. Just in case...
Modern AVR's now offer lossless decoding of DTS Master and Dolby True HD, the two sound formats found on all Blu-ray releases. Also up to 7.1 channels of uncompressed audio and video can be carried by one HDMI cable, greatly simplifying the HT tangle nightmare of years ago. These two key features are something your old AVR does not have and why you should consider a modern HT receiver even if your old Marantz was still functioning properly.
Regret to advise that IMO, you will not get the same quality or power as your old Marantz for $500 or even $800. You will get more features. So if sound quality is paramount, make sure you get an AVR with a full set of pre-outs. If you find the internal amps of the AVR are not cutting it, by having a full set of pre-outs, you can consider adding an external multi-channel amp. But try the internal amps first - that may be all you need.
So without recommending any of the mainstream brands you mention (throw Pioneer Elite in there too), I just want to put forth the above caveats and strongly advise you only consider a model that has a full set of pre-outs. Just in case...