Sigmadrive to Transmission Flange bolts

[fritzdfk]

I have a Sigmadrive with a Yanmar 3HM and KBW10 gear. The Sigmadrive has 4 studs going through the transmission flange and nylocks. The studs have a allen key socket to insert them. The nylocks are on the transmission side of the transmission flange. I recently had two of these studs fall out. The problem is that it is next to impossible to get a tool on the nylocks. A socket and ratchet don't work, a closed end wrench no go. The open end wrench barely engages the nut for 1/8" turn and comes off with any force. I have a wrench with a swivel socket on one end coming but I am not hopeful.

One solution maybe would be substituting a socket head machine screw for the stud and nylock. Another option might be a screw with a 12 point head. Thread locker is required for any of these. Would a high tensile strength screw be as strong as the stud and nut?

[FPNC]

Use 10.9 or 12.9 studs. Use lock washers grade 10.9 or 12.9 and ~all metal~ lock nuts 10.9 or 12.9 grade.

Use red Loctite on the studs and blue on the nuts. Red is also ok on the nuts as it would be very easy to heat them up to remove them if required.