PS. Son said he would be concerned that the wall mud or sheet rock mud wouldn't hold. He said you could lightly sand the paneling, prime it and paint it the groves would still show though. Have to remove it to get rid of the grooves.Sorry I thought my way would work :(
Might be cool to paint it though and use the grooves as a contrast color stripe
Good Morning JO, Having two son's that are in or have been in construction, what comes to my mind is getting some spackling compound or Sheet Rock mud.
Use a putty knife to smooth it in the seams. Then let it dry and sand it lightly. You might need to fill in some places and re dry sand again. With sheet rock mud you can also use a damp sponge to clean it off the other paneling or smooth it out.
It should work. I will call our youngest son later to make sure and write you back.
God Bless you
K. Nana of 5