The 'machine gun' noice is caused by either bad alignment, or a defective Track 1 sensor. Original 1541's didn't have this sensor, and later 1541's have been known to have bad ones.
Have you tried reading the directory from a purchased diskette (as opposed to one you've formatted and written yourself)? The 1541 test/demo disk is great for checking the alignment of the drive.
This rattling can also be caused by inserting a non-Commodore diskette (ie an Apple or IBM diskette). The drive can't read other formats than its' own, so a foreign diskette is the same as a blank one, and the drive will search for quite a while for CBM GCR sync marks before giving up (if it ever does).
A good alignment is a hardware AND software repair. It requires adjusting the stepper motor and using a known good diskette with the proper program to read the diskette, telling you how far off it is and how much to adjust the motor.
I've not seen a Plus/4 version, but Compute's Gazette published a 64 version. I think it was machine language for speed, which is probably why we've not seen a port to the Plus/4. I'll thumb through my old mags and see if I can provide more info on this.