Trouble comparing JSON (or custom PS) objects - powershell

Question

I am having trouble with object comparison.
I have an application which spits out JSON data. Each time I run my script, I will get the current values and import the stored values from the previous run (either from a .json or .xml file). At the end of the script, I will overwrite the stored values with the current values. The data looks like this:
Stored values:
id : 6549888
description : Windows CPU via WMI
name : Test
dataPoints : {#{id=6314; dataSourceId=6549888; name=CPUBusyPercent; description=%
of Busy CPU; alertTransitionInterval=8; alertClearTransitionInterval=0; type=2; dataType=2;
maxDigits=4; postProcessorMethod=expression;
postProcessorParam=100-(PercentProcessorTime/100000); rawDataFieldName=; maxValue=; minValue=0;
userParam1=; userParam2=; userParam3=; alertForNoData=3; alertExpr=>= 50 60 70; alertSubject=CPU
alert on ##HOST##; alertBody=The host ##HOST## is in state ##LEVEL##. CPU is ##VALUE## percent
busy - it has been in this state since ##START##, or for ##DURATION##}}
Current values:
id : 6549888
description : Windows CPU via WMI
name : Test
dataPoints : {#{id=6314; dataSourceId=6549888; name=CPUBusyPercent; description=%
of Busy CPU; alertTransitionInterval=8; alertClearTransitionInterval=0; type=2; dataType=2;
maxDigits=4; postProcessorMethod=expression;
postProcessorParam=100-(PercentProcessorTime/100000); rawDataFieldName=; maxValue=; minValue=0;
userParam1=; userParam2=; userParam3=; alertForNoData=3; alertExpr=>= 90 95 98; alertSubject=CPU
alert on ##HOST##; alertBody=The host ##HOST## is in state ##LEVEL##. CPU is ##VALUE## percent
busy - it has been in this state since ##START##, or for ##DURATION##}}
In this example, someone changed the alertExpr from "50 60 70" to "90 95 98" and I need to catch that (along with changes made to the rest of the properties).
When I run a foreach loop, I am not getting back any differences, but when I look at a single property, Powershell does report the difference. So the following returns nothing:
foreach ($dataSource in $currentDataSources) {
foreach ($recordedDatasource in $previousDataSources) {
If ($dataSource.id -eq $recordedDatasource.id) {
Compare-Object $dataSource $recordedDatasource
}
}
}
But looking at the index 1034 (that's my test item) does show a difference:
Compare-Object $currentDataSources[1034].datapoints.alertexpr $previousDatasources[1034].datapoints.alertexpr
What is the best way to check each of the properties between my to sets of data?
Thanks.