Yes, but it is unlikely you need a whole analogue board. There is probably one or two components on the board that can be easily replaced. Better than become yet another disposable "consumer" in the world, invest a bit of time in learning to repair the Mac Plus if you are going to be part of the vintage Mac community. Eventually, all of these old compacts will "get roasted" which means even eBay will not help you keep your interest in old Macs going. By all means pick up another one so you don't have to miss a day without using an old Mac! But don't throw the old one away, or shove it into a box in the back of the garage where it will only fall into further disrepair, or even gut it into a Macquarium.
What exactly do you plan to do with the old Mac Plus?