I moved & lost the top mounting bolts for my LG microwave. Model LMVM2055S7. I don't what size the bolts are.

Only gravity keeps the door in open position. You can try to tilt front down by loosening the top mounting bolts.

Perhaps 3/8 bolts. Get one and try it in the mounting hole. Also measure to see how long they need to be to anchor to the cupboard. Length is pretty important as they won't work if too long.

Look for back mounting bolts location, find your wall studs location and mount from the back

every over the range microwave is 30" wide. all other measurements can vary. be prepared to change the wall mounting bracket and drilling new holes for the top mounting screws.

Unplug the range and move it out of the way.
Open the cabinet above the microwave.
Unplug the power cord.
Remove the 2 bolts going through the cabinet into the top of the microwave.
Have a helper hold the microwave in place before these bolts are removed.
After the bolts are out,assist the helper by lowering the front of the MW and lift the back of it off the mounting bracket attached to the wall.
They are heavy and awkward.
A helper must be used.

mcdevito75 here, Best Bet bring the mounting bracket and bolts recieved with the unit to your local hardware store. they will give you the correct bolts need to mount undera cabinet.

Jim here. In cabinet above microwave, locate 2 mounting bolts.
Place a box on the stove top to support the microwave once the mounting bolts are removed (you may wish to cover the box with a thick towel or small throw rug).
Procedure:
1. Unplug microwave.
2. Remove both mounting bolts from top of microwave (they secure it to the overhead cabinet).
3. With microwave front angled down onto box, pull some of power cord out of hole (to provide some moving space).
4. With microwave hand supported, remove box from stove top (a second set of hands would be helpful here).
5. HARD PART- detach top of microwave back from wall mounting plate by placing a hand under the bottom rear of the microwave and pushing up. (Wall mounting plate is screwed into the wall behind the microwave and provides both top and bottom support to the back of the microwave.)
6. Lower front of microwave until you can see about a 1-inch clearance between the top-rear of the microwave and the cabinet above it.
7. Firmly lift the microwave straight up and then bring forward. It should be free of the wall mounting plate.

check tha back of unit.

You may be looking for the philips flat head 1/4 x 28 tpi (threads per inch) threaded bolt that is about 4" long. The tip of the bolt does not have threads, which aids in locating the threaded hole in the top of the microwave:

General Electric's part number for their OTR microwave cabinet mounting screw is WB01X10180 (or AP3205964 or 942461 as listed on some repair parts sites).

A set of three is GE's p/n WB01X10125 (or AP3185225 or 910236 as listed on some repair parts sites).

This flathead screw is used on most Advantium Speedcook microwave ovens such as the SCA2001BSS03 or SCA2000FWW03 or SCA2001KSS03.

Here's a picture of three screws:

If the OTR is the same model, the mounts should be the same. As long as you use the same bolts/screws from the old one, or the same length new bolts/screws, it should be a fairly simple exchange.