Did you try removing the hose adapter as suggested? If you need a float/diverter valve, this should work:
Amazon.com: Pentair 08650-0079 Float Assembly with O-Ring Replacement Sta-Rite U-3 Pool and Spa Skimmer: Garden & Outdoor
www.amazon.com
You'll need to remove the basket to connect the vacuum hose or buy a
separate vacuum plate that sits on top of the basket. Either way, you can't skim and vacuum at the same time. The advantage of the skimmer plate is that it will catch the debris before they reach the pump basket.
Most of us with suction cleaners don't use them as the primary suction source when the pump is running. Your skimmer should be active most of the time. Ideally, most debris that fall into the pool will be remain on the surface and end up in the basket. What the skimming action misses ends up at the bottom and is picked up by the cleaner. I run my cleaner a couple hours every other day or so.