Our ice maker jams up; the ice doesn't dump out and the ice turns into a solid block all through the icemaker. If we defrost the ice maker and reinstall it will it work again or do we need to replace the whole unit?

You have dirty coils under the unit, most likely. It's not freezing like it should and when it goes into defrost it melts the ice together. Clean the coils and the fan with spray soap and spray it with water to wash the dirt and dust off. After it is clean then you can see if there are any other problems.