Fixing Bowed Walls on a 4×6 Log Home

Hi,We have a log home (4”x6” milled logs) that is 26×42 feet. One end (26 feet) has been bowed outward for a number of years. The bottom half of the wall is fine across the 24′ length. However, the upper half starts to bow outward near the middle of the wall length and by the top of the wall it is now out about 1 1/2 inches from the bottom. The logs are nailed together with 6” barn spikes and have two beads of expandable foam (similar to Red Devil foam) between each row. Is there any way