Steve
That can happen to anyone so don't beat yourself.
Ken
The IP extensions are thin plastic sheet trimmed and Tenaxed on. I then added the lip on the IP top from very thin plastic sheet and Tenaxed in place. Things were then sanded to blend in the joins. The control column is stretched sprue and secured with Tenax.
Here's a bit more info on the K:
Reading from the A-26 Invader in Action Squadron Series book, it details that the K's were highly modified by a firm called On-Mark Engineering Company located in Van Nuys, California in 1964. The wings were strengthened and rebuilt and the fuselages remanufactured without the turrets. They added the beefier KC-135 brakes and tires, Pratt & Whitney R-2800-103W, a monster prop, wing tip tanks, enlarged dorsal fin and updated avionics. They served with the USAF 609th SOS well into late 1969. The last known fully armed Invader in military use made its last flight in July of 1977 under Indonesian Air Force service.
The Invader aircraft had quite a colorful and long service record starting in WWII, and going thru Korea, the Congo, Angola, Cuba and Nam.