Here's a long shot ... as your R/A CD50 is an older model ... some of the lubricant on the CD sled guide rails may have dried and hardened in some spots … when the sled hits one of these dry patches it will be slowed or stalled not allowing the laser to lock correctly with the spinning disc … once the laser sled passes over/through this spot ... it should regain the correct lock with the CD data stream and stop skipping
Can you remove the cover and locate the lased transport system and see if you can gentle clean the rails
Good luck