I have an old - 1973 vintage - walk behind rotary hoe. It is fitted with a horizontal single cylinder KNDR70 motor. The motor is fitted with an oil pressure indicator on the head on the right hand side. This indicator is a small brass rod that rises into a plastic veiwing cover when oil pressure is ok. I have lost the plastic cover. Has anyone replaced this indicator with an oil pressure gauge on this type of motor? Has anyone got any ideas of problems I may encounter? My late father bought the machine new and it has done fantastic work over the years.