I often use the above site to get manuals, usually when helping members here.
I have used this site for years without incident. They have been a good source for manuals and you don't pay for them. Three days ago I went to the site to help a member with an older Pioneer receiver. I went on to that site, found the manual and looked at the index, when I clicked on the relevant page, a large red notice went up with white type, and a voice continuously repeated that my computer was insecure and had been locked for security reasons and not to turn off the computer as all data would be lost. The message contained a number to contact Microsoft to rectify the problem. I immediately recognized this as a scam and turned of my computer, which I had to do with the off button and not the mouse, as my computer was locked. Fortunately my computer did shut down and restarted again. Periodically it said that Windows Defender was disabled, which it was not.
Anyhow, I had my eldest son do a forensic analysis of my computer. He is chief software engineer and in charge of security for Lumi. He is experienced in forensics of computer systems.
He was able to trace the course of events including the page I was on, when the incident occurred. Anyhow as soon as the incident occurred I was sent to a site in Russia, and then to some radio station in California and then to a vast number of sites all over the place.
Anyhow it seems nothing has been left on this computer and I am in the clear.
On searching this according to Reddit, this site Manualslib.com has been known for this for at least 2 years, but obviously I was unaware.
My son did go to the site and to the page where this incident occurred with extreme care and protection and could not reproduce the hack yesterday.
I am posting this here, as I know other members have used this site as well. Unfortunately my advice has to be to stay away from this site.