Karl is a great resource and was very, very helpful when I had a Linotype Topaz scanner!
When I considered having him in to tune my scanner(since sold as I am downsizing and the Topaz has a large foot print) he was MUCH less expensive than Heidelberg for more work on the scanner (Heidelberg set a time limit on the tune up, which includes travel time, if it is not finished in that time limit, over time, Karl offered a flat rate full tune up).
Good luck, I hear the Tango is a great scanner, please let us know how it works out.
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