the lasers inside them players don't last forever man! Sony uses two of them. One for SACD and one for red book, maybe Denon does too.... sounds like they do to me from the OPs thoughts here.
I've heard from modders and sellers of Denon getting a trouble free one is the task at hand. A good one lasts a good long while without issue... while other's routinely do not and require lasers and other replacements now and then.
Add in the changes/improvements in digital playback, I'd look for a current CDP and maybe not a Denon... or another Denon that has been escalated performance levels via mods. The Mod Right 3910's are highly touted machines. A fully modded one keeps company with CDPs rangin well into the $6K arena.
Or you can have another laser installed for about $150 or so. I think it's like the Sony in that both lasers and motor are done at the same time.... or for $500 I'd just do me an Oppo BDP 83 and be done... or for about $250 the DVH 83 non Blue ray unit preowned... if you can catch one quick enough.
I gave up trying and just bought the BDP 83 instead... glad I did too. think SACD is great sounding, wait till you hear Blue ray audio.
Lots of options... do have fun.