Alignment of Generator with Gear Box Coupling

Installation (Anchoring and Grouting) of SIEMENS SST-400 turbine (Turbine+ Gear Box+ Generator) has been completed. Final alignment of turbine coupling (flexible) with gear box has also been successfully finished.
But there is a mistake found before the final alignment of generator coupling with gear box coupling. This coupling is rigid (not flexible) and the Gap between generator and gearbox coupling is 31 mm instead of 17mm. The difference of 14mm is very huge as the STG is very precise equipment. All the installed pipelines for Oil and cooling water as well as bus-bar have been completed with generator and gearbox, these will have to be dismantled, generator shall be re-lifted and auxiliary system will have to be erected again. These additional works are very time-consuming and costive.
I need purely technical suggestions to solve this problem. Whether there is solution of this problem without disturbing the auxiliaries’ work, if it is then please share. Or either will have to dismantle all and perform the levelling again?