The Prusa plain PEI bed seems to have good adhesion al by itself for PETG (Amazon Basics brand). I tried Chuck’s tip of using a bit of Windex as the bed approaches final temp - way too much adhesion. Simply cleaning the bed with alcohol and printing is showing good first layer adhesion and easy release. For now anyway.
I have had good luck maintaining adhesion on the Prusa PEI bed with a quick wipe of 90% isopropyl alcohol before each print starts; until just the other day. Went back to the Prusa support and they say to wipe the PEI bed with acetone once a week. Did that last night and good adhesion returned.
See the 10:15 mark in the following support video by Joe Prusa:
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