Dishwasher partially fills

The cycle time of my GE Adora QuietPower 3 (GHDA670N00BB) has gradually increased while the cleaning performance has decreased. The Speed Cycle (without added heat or heated dry) is 64 minutes, up from 47 minutes a couple of years ago. Yesterday, a relatively small load of dishes were left covered in detergent. After thoroughly cleaning the machine, I found that it barely fills to the bottom of the float tower (well below the heating element). I replaced my whole-house water filter cartridge and saw no improvement. To verify adequate water supply, I filled the tub directly from the flexible supply line. It took under 40 seconds to reach half way up the float tower. I then removed and cleaned the fill valve and strainer with no improvement. Finally, I used a used a non-contact voltage tester on the solenoid valve and found that it stays energized for just 43-45 seconds. I have read elsewhere on this forum that the fill time for other GE models is 70 seconds. Am I correct in assuming the same is true for this model? If so, does that indicate that the main circuit board needs replacing? Thanks!