Hi Grumpy,
Thank you very much for going in to detail about this. I have spoken to a friend of mine who welds garages together for a living and he has very much concurred with your statements and gone as far as saying basically spotting it with a MIG Welder along each crack but spotting it at alternate ends of each crack without heating the metal up to any real extent thus avoiding distortion and keeping it to an absolute minimum. Clamping the sides (with the sole plate and front roller installed) to a solid metal bench and then clamping a solid metal bar to the underside of the rail to hold it perfectly straight is all part of the exercise he claims.
I totally agree with you about the comments you made on the thread you pointed out about the structural integrity was completely compromised on that other earlier SB / Rover faker machine with the totally failed rail. That one would have been "shakin' all over" like a 1950's rock n roll outfit.
BTW I have already purchased a twin set screw clutch body to replace the defective old captive cotter unit.
Once again thank you very much Grumpy for your detailed input as its always great to get fresh ideas from a different source and angel, that's for sure.
Cheers,
BB. (Marty)