chkdsk /r

Is it safe to power down a PC when it's on stage 5 of chkdsk /r?? This is the 'verifying free space' stage and I think the HD has crashed or locked up. It completed stages 1 thru 4 and MANY problems were found and corrected, but now it's stuck at 0% on stage 5, and the hard drive was making a very regular click about every 4 seconds; it was a soft, quiet click, but now it is not so regular. It's making the same click but at seemingly random intervals, and it's been at 0% in stage 5 for maybe 30 minutes now (I'm running it on an older HP a650e).... So I want to reboot and run a drive diagnostic but don't want to risk damaging the drive if it's healthy.....

EDIT- nevermind.... it has finally gone past 0%; it is now at 29% and slowly climbing