Thanks for the comments all, you were quite right the issue with the unit was most likely too little water as now it's back together and good water flow all is working fine with the belt speed as it was. In the end I made a new lower wheel support and shaft assembly as the originals were deemed not worth saving. I have put some pics up of the linisher and the components for anyone interested.
The linisher
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(31kb)Lower wheel and support components
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(104kb)
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(41kb)for scale the lower wheel in the shots is about 230mm (9") diameter and weighs 39kg (86lbs)