Is the front pilot truck on your k-27 broken? I had no idea mine was until I took a closer look after a friend alerted me to the problem earlier this year.
He sent me a potential solution to 3d print, designed by Dylan Huston.
The one issue I had with the design was the use of an active bistle post, which required a new hole to be machined in the deck plate. Dylan is a skilled machinist, but most folks would have trouble machining this hole. I also noted that the existing brass pin with the spring behind it was digging into the bottom of the pilot deck surface.
This new design solves several problems. It uses a 1/8 thick piece of brass as the base of the truck. It utilizes ball bearings to fit on the existing axle with a little polishing. The remainder is 3d printed parts in Formlabs Tough 2000 resin that I have found to be impervious to breakage. The bump stop on the top is designed to slide easer on the bottom of the deck plate. So it is very durable, and with the low slung brass frame tracks much better. I cannot guarantee you will be derailment free, but your new front truck is reasonably indestructible.
I currently have the first batch of these in service with several owners
For a limited time (depending on demand) I am offering a kit for this new pilot truck for $30.00 plus $10.00 priority mail shipping. I can fit up to three kits in a small flat rate box, if you need more than one.
At this time I am looking for reservations. I need to purchase the brass frames in min lots of 12 pieces to make this price work, and I am not making a lot of $$ here either, more so looking to keep these locomotives going for years to come.
Please send me a PM on this forum to make a reservation. Please include your shipping address and contact email, so when ready I can send you the info for a PayPal payment, or contact info if you wish to send a check.
Al P.