Did you change your mapping? The mapping file no longer points to a repeating group, thus the ID parameter would have to be the full path to the ID node instead of a relative path. Your current mapping file has "my:myFields" for the repeating group - your previous mapping file had my:myFields/my:Items/my:Item
Here's the mapping file you are currently using:
<my:Mappings>
<my:IsRepeating>true</my:IsRepeating>
<my:RepeatingGroup>my:myFields</my:RepeatingGroup>
<my:Mapping>
<my:FormField my:IsRichText="false">my:Items/my:Item/my:serial</my:FormField>
<my:SharePointColumn>Title</my:SharePointColumn>
</my:Mapping>
<my:Mapping>
<my:FormField my:IsRichText="false">my:Items/my:Item/my:partno</my:FormField>
<my:SharePointColumn>partnumber</my:SharePointColumn>
</my:Mapping>
<my:Mapping>
<my:FormField my:IsRichText="false">my:Items/my:Item/my:customerinfoline1</my:FormField>
<my:SharePointColumn>cusinfo1</my:SharePointColumn>
</my:Mapping>
<my:Mapping>
<my:FormField my:IsRichText="false">my:Items/my:Item/my:customerinfoline2</my:FormField>
<my:SharePointColumn>cusinfo2</my:SharePointColumn>
</my:Mapping>
<my:Mapping>
<my:FormField my:IsRichText="false">my:Items/my:Item/my:datemfg</my:FormField>
<my:SharePointColumn>datemfg</my:SharePointColumn>
</my:Mapping>
<my:Mapping>
<my:FormField my:IsRichText="false">my:Items/my:Item/my:hoselot</my:FormField>
<my:SharePointColumn>hoselot</my:SharePointColumn>
</my:Mapping>
<my:Mapping>
<my:FormField my:IsRichText="false">my:Items/my:Item/my:fitting1</my:FormField>
<my:SharePointColumn>heat1</my:SharePointColumn>
</my:Mapping>
<my:Mapping>
<my:FormField my:IsRichText="false">my:Items/my:Item/my:fitting2</my:FormField>
<my:SharePointColumn>heat2</my:SharePointColumn>
</my:Mapping>
<my:Mapping>
<my:FormField my:IsRichText="false">my:Items/my:Item/my:sonumber</my:FormField>
<my:SharePointColumn>sonumber</my:SharePointColumn>
</my:Mapping>
<my:Mapping>
<my:FormField my:IsRichText="false">my:Items/my:Item/my:ReviewStatus</my:FormField>
<my:SharePointColumn>ReviewStatus</my:SharePointColumn>
</my:Mapping>
<my:Mapping>
<my:FormField my:IsRichText="false">my:Items/my:Item/my:Etching</my:FormField>
<my:SharePointColumn>Etching</my:SharePointColumn>
</my:Mapping>
</my:Mappings>
Here's the one you were using before:
<my:Mappings>
<my:IsRepeating>true</my:IsRepeating>
<my:RepeatingGroup>my:myFields/my:Items/my:Item</my:RepeatingGroup>
<my:Mapping>
<my:FormField my:IsRichText="false">my:serial</my:FormField>
<my:SharePointColumn>Title</my:SharePointColumn>
</my:Mapping>
<my:Mapping>
<my:FormField my:IsRichText="false">my:partno</my:FormField>
<my:SharePointColumn>partnumber</my:SharePointColumn>
</my:Mapping>
<my:Mapping>
<my:FormField my:IsRichText="false">my:customerinfoline1</my:FormField>
<my:SharePointColumn>cusinfo1</my:SharePointColumn>
</my:Mapping>
<my:Mapping>
<my:FormField my:IsRichText="false">my:customerinfoline1</my:FormField>
<my:SharePointColumn>cusinfo2</my:SharePointColumn>
</my:Mapping>
<my:Mapping>
<my:FormField my:IsRichText="false">my:datemfg</my:FormField>
<my:SharePointColumn>datemfg</my:SharePointColumn>
</my:Mapping>
<my:Mapping>
<my:FormField my:IsRichText="false">my:hoselot</my:FormField>
<my:SharePointColumn>hoselot</my:SharePointColumn>
</my:Mapping>
<my:Mapping>
<my:FormField my:IsRichText="false">my:fitting1</my:FormField>
<my:SharePointColumn>heat1</my:SharePointColumn>
</my:Mapping>
<my:Mapping>
<my:FormField my:IsRichText="false">my:fitting2</my:FormField>
<my:SharePointColumn>heat2</my:SharePointColumn>
</my:Mapping>
<my:Mapping>
<my:FormField my:IsRichText="false">my:sonumber</my:FormField>
<my:SharePointColumn>sonumber</my:SharePointColumn>
</my:Mapping>
<my:Mapping>
<my:FormField my:IsRichText="false">my:ReviewStatus</my:FormField>
<my:SharePointColumn>ReviewStatus</my:SharePointColumn>
</my:Mapping>
<my:Mapping>
<my:FormField my:IsRichText="false">my:Etching</my:FormField>
<my:SharePointColumn>Etching</my:SharePointColumn>
</my:Mapping>
</my:Mappings>