Hm I tried a couple of Verbatim DVD-R and DVD+R, both jewel case (printable) and cakebox, and results are not impressive. Maybe the time when really great DW1620 have been produced is over? Otherwise it would mean all media on sale here (4 different shops) is not as good as it used to be... maybe I will waste just one more DVD+R made in Singapore for testing, have to see.
In which regard is your new drive "worse" than the old one? PIE/PIF? I do not even get nearly as good scans as others, and scans of dvd-r media get worse with every scan. Was told to check my power supply and already took some stuff out, but I did a fast calculation and still have 15-20% less power consumption than supply.
Also none of the currents has less than 10% reserve and the much more power-demanding LG (5 Watt more than the BenQ) works great.
All the best!