Manual Calibration of an FLSUN kossel mini

I have created my own problem with my printer, the result is the above printer equipped with an MKS-BASE controller and no probe for auto calibration, I cannot see an easy way to adapt a probe when the printer does not print. I am using Marlin with Repetier and following Tom’s guide video. I have the Delta Height measured at 277.2mm, the arms are 222mm and the Delta radius 100mm. The delta height at each tower is Alpha=276, Beta=276.1and Gamma=276.2mm.
My version of Marlin is V1.0 and does not contain Delta Smooth Rod Offset coding and I am unable to adjust for the convex movement of the nozzle.
Can anyone help?