My father wore this watch for as long as I can remember. It has huge sentimental value to me.I had the crystal replaced as it was very badly scratched and the watch repair has quoted AUD$300 to clean and repair the face. Without knowing the value, it is difficult to gauge if this is reasonable.Can anyone help? There are no markings on the back and I didn't think of asking the watch guy to look for the internal serial number when he replaced the crystal. Really just want an estimate of the date!Thanks in advance.