Zetor 4511 main clutch levers

Thanks to help received on here, we have been able to ascertain what our clutch issue is. All of the three main clutch levers are badly worn down on the end and one of the springs had snapped. Replacement bits are easily sourced but am getting mixed advice as to whether the repair can be undertaken through the inspection hole. The levers are easy to access and change but the spring is under tension and not sure if a special tool is needed? Also is there a certain gap required when installing new lever? Apologies if Ive asked similar questions before....trying to avoid splitting the tractor if possible!! Thanks in advance.