4 and also 3 years ago I had to send my Cambridge 840C in for repair, once under warranty and once out of warranty.
First time it was a connection that had come undone, the second time it was a faulty power supply. 2 breakdowns in the span of less than 2 years. Both times it was serviced, it was returned to me in working order. After those incidents, later it developed an intermittent nuisance problem - every couple of weeks the unit would freeze=up and not respond to commands, I would have to completely power it down to get it to work. I would rate my experience with the 840C on the low end of reliability given my better experiences with owning other cd players.