Have some problem with enlarger stand.Second hand enlarger in very nice condition,Nikon lens, but it was imposible to have sharp photos from sharp negative.Enlarger wooden stand was bending in the middle for about 4 mm.Stand is wide 40 cm (16 inch).Maybe this can help...
Are you refering to the baseboard? They can be replaced or the enlarger bolted directly to the counter top, or wall with a special bracket. Have you aligned the machine? This is as simple as checking the head for parallel with the base on an X and Y axis.
4 mm bend is... so small.
i tried to make 2 enlargments with 2.8/50 el-nikkor at 17x ratio, f/5.6, one perfectly sharp (peak 2000 loupe used) and second one held cca 2 cm above the enlarger board (i put the paper on some box). hard to tell the difference unless looking at the grain itself from a very small distance!
As I see it, there are several solutions.
1)replace the base board with MDF or plywood. I made one with one 12mm layer of each glued together. This is probably the best & most expensive.
2)Turn the board over & screw it it to MDF or ply.
3)Screw it to two or three metal angles to pull it straight.
2 plys of 3/4" wood, laminated w/glue and a few screws = very solid (heavy, but solid) baseboard. But yeah, after replacing the baseboard, check the alignment, it sounds complex but isn't.