I present this in the context of trying to understand what may play a role in a timeline study of the h-/h+ issue, which is believed to have begun sometime between 2004 and 2008 (between Run 4 and Run 8).

select concat(IF(cage,"OFC","IFC"),IF(side,"W","E")) as fieldcage,ring,
 min(MissingResistance) as minMissingRes, max(MissingResistance) as maxMissingRes,
 max(resistor) as externalRes,min(beginTime),max(beginTime) from tpcFieldCageShort
 where ring!=0 and deactive=0 group by ring,side,cage order by min(beginTime) asc ;

Results:

fieldcage	ring	minMissingRes	maxMissingRes	externalRes	min(beginTime)		max(beginTime)	
IFCE	169.50000000	2.00000000	2.00000000	2.00000000	2003-12-01 00:00:00	2007-03-01 00:00:00
IFCE	115.50000000	2.00000000	2.00000000	0.00000000	2005-01-10 00:00:00	2005-01-10 00:00:00
IFCE	168.50000000	-1.00000000	-0.50000000	0.00000000	2006-01-01 00:00:00	2007-03-01 00:00:00
IFCE	170.50000000	-1.00000000	1.62828004	1.50000000	2006-01-01 00:00:00	2007-03-01 00:00:00
IFCE	181.50000000	-3.00000000	-1.00000000	0.00000000	2007-03-01 00:00:00	2007-05-23 14:00:00
IFCE	180.50000000	0.00550000	5.42943001	0.00000000	2007-03-22 21:48:48	2007-06-26 15:50:19
OFCW	80.50000000	0.00000000	0.34500000	0.00000000	2007-03-26 02:13:12	2009-06-21 05:06:22
OFCW	181.50000000	1.79999995	1.79999995	0.00000000	2009-05-25 22:50:00	2009-05-25 22:50:00
OFCW	170.50000000	2.00000000	2.00000000	0.00000000	2009-05-25 22:50:01	2009-05-25 22:50:01
OFCW	181.39999390	1.78100002	1.78100002	0.00000000	2009-05-25 22:50:02	2009-05-25 22:50:02

Some of the history has been Field Cage Shorts.

Notes:

1. The IFCE short at ring 115.5 was only recorded briefly (for about 10 days in early Run 5).
2. The OFCW intermittent short on ring 80.5 started during Run 7 and was no longer seen after Run 9.
3. The short on IFCE near rings 168-171 started just before Run 4 (at the end of 2003), a permanent patch was implemented in October 2005 just before Run 6 (recorded as 2006-01-01), and a better permanent patch was made before Run 8 (summer 2007). The first permanent patch still experienced some shorting, so there are DB entries for the short in Runs 6 and 7. However, for Run 7, we shifted the location of the fluctuations from near ring 170 out to near ring 180 (as if it were a different short). The better patch (and any cleaning we did) worked well enough to eliminate the fluctuating currents.
4. Before Runs 8 and 9 (2007-09-01 and 2009-02-24), the table was reset to all zeros, and we applied only the OFCW ring 80.5 short (using elementID 5 for Run 8 and elementID 1 for Run 9).
5. A new short appeared at the end of the OFCW chain when the magnetic field was flipped near the end of Run 9, on 2009-05-25. There are three entries for this issue, but only the last one is in use (the others were early guesses).
6. For Run 10, we made no new entries in the table, thus using only the OFCW short at the end of its chain (the short at ring 80.5 remained listed in the DB but with a short of 0 ohms).

So the OFCW short at ring 80.5 was new between Runs 7 and 8, and there were modifications to the shorts in IFCE during and between Runs up until just before Run 8. If the problem is a distortion on the east side, is it possible that we have not been correcting properly for something in the IFCE since Run 7? The field cage current recordings are available are perhaps should be re-examined for confirmation.  

-Gene