Where can I get a repair manual for my Brother XL-3030 sewing machine?

you may be able to enlarge the manual page:

Brother XL 3030 User Manual Page 60

The hook (half-moon piece) needs to go in first, but you may need to wiggle it to seat it and then hold it while you fasten the outer retaining ring (hook race). Flip the levers up to hold the ring in place. Then install the bobbin case.

How to Clean and Maintain your Sewing Machine at Home Front Loading Bobbin

FWIW, my machine oiling instructions say to apply a drop of good quality oil on the outer edge of the hook race lip where the hook rubs as it turns. But, your manual should explain where to oil.

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Check that the LCD screen adjustment has not been dimmed or darkened. If that is not the case, then a component is or has most likely failed.

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My brother XL-3030 will not sew, the light comes on but the machines does not engage to sew when you press the foot pedal. Plus the led screen is blank. Is it the internal computer or the power cord?

check with sew4less.com

Esto es del sitio web de brother
http://www.brother-usa.com/ModelDocuments/Consumer/Users%20Manual/UM_XL_3025_3027_3030_EN_447.PDF
Esta en Ingles y Espanol.

if you want it repaired look the phone book for a sewing machine repair shop

or if you want to buy a new one here are 2 websites to check with

sewingpartsonline.com

sewingmachineparts.net

check your drive belt sounds like its off or broken

Free download here - http://www.brother-usa.com/ModelDocuments/Consumer/Users%20Manual/UM_XL_3025_3027_3030_EN_447.PDF

it is easy to switch the stich modes
there are two wheels on the side on the mchine
one in for manualy stiching *the big one)
and the little one changes the stitch
you have to look at the LCD screen to make sure the numbers correspond

Have you checked the manual?