Michell Gyro Se running a little slow

I have noticed that some songs sound slower off my table than they should. This is most evident on Led Zeppelin's Whole Lotta Love, Simon & Garfunkel's Cecelia and The Smiths' Frankly, Mr Shankly. Most of the time, the difference is not noticeable, but on some songs I can pick it up. I'm not sure what the problem is. I have the external power supply but am not sure if that is the issue.
Do you have the stock power supply or the PSU upgrade? Both do have speed adjustments, but you have to open up the stock power supply to get to it. I use the Kab Speedstrobe to check my speed.
try another belt before you panic.
I have the PSU upgrade and I have not tampered with the speed on it yet. I think that might be the issue. As for the belt, the table is less than a year old, although it was a dealer demo, do you still think that could be the problem.
If you haven't cleaned the bearing & well and refilled it with the proper lube, that might help as well. Make sure it's smooth and free spinning.
I own a Gyro SE MK II , yes check the belt and Plato's suggestion for lube and clean free moving bearing before you panic. I noticed the same as you only on certain albums so got a new belt and that corrected it but I cleaned and relubed anyway. Also check that the belt is in the proper groove ON THE PLATTER as per the manual. Cheers
Thinking that your turntable runs slow is one thing. Actually running slow is another. Use an inexpensive strobe to determine if it is, in fact, slow. Many other components have an effect on PRaT which can give the impression of slow speed. Then again, if you are blessed/cursed with perfect pitch, you can pretty much be assured that it is running slow.
The bearing and well are key to keeping the unit from running slow. The michell gyro inverted bearing has a pumping system that moves oil up tothe bearing. low oil or dirty oil can cause issues The other possibility is the bearing is bad. It is unlikely, but I have seen that once on my michell.
I checked the oil first thing so I don't think that is the issue. I actually filled the oil well a little while ago. I'll check the bearing to see if that is the problem and get a strobe as well. Viridian, what can I check on my other components to see if the problem is elsewhere.
Check to see that the main screw under the spindle is tight. If not fully tightened at installation it can become loose resulting in a lower speed. Had this problem some time back. Need a coin to fully tighten it.
Get the KAB speedstrobe or another strobe and check the speed. Since you have the HR Power supply it's easy enough to adjust it. My Gyrodec was running about 1% fast prior to adjustment. But I never had a wow-flutter problem.

So, as has been mentioned:
--Make sure bearing is lubed and clean
--Clean your belt
--Clean the pulley an the groove on the platter
--check speed with strobe (you can also use a generic strobe disk from Vinyl Engine, with an incandescent light. Just not as accurate and a little hard to see)
--Try with the standard power supply to see if you have the same problem/issue
--Grab a piano album and make sure the notes don't sound 'sour' or vary during sustained notes
By the way, I found Pledge Multi-surface cleaner very good for cleaning the platter.
I have an Orbe with the AC motor. Get one of these for $25.
It's cheap and you can run a LP with it to see if indeed you are running slow. Usually as a belt gets older it starts to shrink or harden and it causes the TT to run a bit fast. I used the Wally tools to test speed but the LP had a slight warp in it and caused a error in the read so I bought a laser photo tach and it worked great. If you can adjust your PSU your better off than me. The QC PSU has no voltage adj., so the motor pulley is what really decides your speed. I have two and one runs a bit slower than the other.
I agree that other things may be at work but it should show up on more than just a few LP's no matter what the cause unless its in the LP(?)

I bought themeter you recommended and it arrived today. I also have an Orbe. Can you explain how to use the meter? Do you tape the reflective tape to the side of the platter? From the instruction that came with it, it seems to suggest that I cut one 0.5" square reflective tape, then tape it to the side of the platter, align, and measure. Is that correct?