I use various measure equipment to work as
an engineering consultant.
pH meter, DO meter, electric conductivity
meter, thermometer and so on.
Except the thermometer, there is need to maintain
periodically.
Because if the performance of measure
equipment is bad condition, I can hardly do accurate or proper technical
advises.
As the condition of DO meter was wrong, I changed
battery and internal liquid of the equipment.
As a result, it could be recovered.
However, the work that I put small o-ring in
the sensor by using tweezer was a troublesome task for me, although I could do
easily in my younger days.
Am I presbyopia?