An existing industrial 3D printer was bought for $100,000 three years ago. It currently can be sold for $40,000. This printer can be kept for two more years from now with an operating cost of $5000 in year 1 and $7000 in year 2. If it is kept for one more year and then sold, its market value will be $28,000, and it will be worth $12,000 if it is sold after two years.

A new and more advanced 3D printer can be purchased for $120,000 with a useful life of 7 years. If it is kept for one or two years and then sold, it will have an operating and maintenance cost of $12,000 per year. If it is kept longer than 2 years, it cannot be sold until the end of year 7. In that case, it will have an operating and maintenance cost of $16,000 every year. The market values at the end of years 1, 2 and 7 are $95,000, $80,000 and $9000, respectively.

Based on this information, when is the best time to replace the existing 3D printer? Provide your detailed analysis and calculations. (MARR is 10% per year)