You're going to have two tables (at least). Spreadsheets work differently than databases, which do not like to duplicate information. Because a relational database (Access, for example) can relate entries on one table to another, you can enter the MRA, CK#, Cust#, Invoice#, Debit Amount, Date, once for a record and then enter subrecords detailing the Part Numbers, Item Numbers, Qtys, Costs, and DMR#s. The main table (the one you have now) will have those first six fields. The subtable will have the latter grouping, plus a field of the same type as the identifier field (MRA? CK?) from your main record (whatever uniquely identifies that record - it may be more than one field). So if the identifier is an autonumber, it needs to be Long Integer. If it's Text, it needs to be text.
Go into Tools>Relationships and draw a join between the two matching fields in your tables. Check Referential Integrity and Cascade Update, Cascade Delete. You should end up with a One-to-Many relationship.
Now if you build a subform with these "repeating" fields and move them off your main form, you can go to one record once, enter the identifying information, and then go to the subform and enter all the parts/items/whatever you need to. Make the subform a Continuous Form probably.
Further addendums..addenda?:
You have a field called Debit Amount, and then one in the repeating fields called Cost. Is the Sum of Cost = Debit Amount? If so, you may not need to store it in the main record.
Field names with special characters besides the underscore in them can give problems. Access is more forgiving than most database systems, but consider renaming things like CK#, Cust#, Invoice#, etc. CustNo would be a good substitute, or CustNum/CustomerNumber.
Sorry the SetFocus thing didn't work out. However if you structure your data properly you shouldn't need to use it anymore.
Look up an article, book, or topic here in the forums about 'database normalization'. Especially if you're coming from a spreadsheet background, this will be invaluable to let you know how to work around these problems properly.
Your report can have subreports if you need to detail these sections. I've even used my subform from my form as the subreport and it comes out nicely if I have it formatted properly.
Good luck,
David R